chore: Deprecate QueryUpgradedConsensusState (cosmos#9906)

## Description

Closes: cosmos#9855 

Deprecate `QueryUpgradedConsensusState` from x/upgrade

---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

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I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -98,6 +98,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/bank) [\#9832] (https://github.com/cosmos/cosmos-sdk/pull/9832) Account balance is stored as `sdk.Int` rather than `sdk.Coin`.
 * (x/bank) [\#9890] (https://github.com/cosmos/cosmos-sdk/pull/9890) Remove duplicate denom from denom metadata key.
 
+ ### Deprecated
+
+* (x/upgrade) [\#9906](https://github.com/cosmos/cosmos-sdk/pull/9906) Deprecate `UpgradeConsensusState` gRPC query since this functionality is only used for IBC, which now has its own [IBC replacement](https://github.com/cosmos/ibc-go/blob/2c880a22e9f9cc75f62b527ca94aa75ce1106001/proto/ibc/core/client/v1/query.proto#L54)
+
 ## [v0.43.0](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.43.0) - 2021-08-10
 
 ### Features

docs/core/proto-docs.md

@@ -9315,7 +9315,7 @@ Query defines the gRPC upgrade querier service.
 | ----------- | ------------ | ------------- | ------------| ------- | -------- |
 | `CurrentPlan` | [QueryCurrentPlanRequest](#cosmos.upgrade.v1beta1.QueryCurrentPlanRequest) | [QueryCurrentPlanResponse](#cosmos.upgrade.v1beta1.QueryCurrentPlanResponse) | CurrentPlan queries the current upgrade plan. | GET|/cosmos/upgrade/v1beta1/current_plan|
 | `AppliedPlan` | [QueryAppliedPlanRequest](#cosmos.upgrade.v1beta1.QueryAppliedPlanRequest) | [QueryAppliedPlanResponse](#cosmos.upgrade.v1beta1.QueryAppliedPlanResponse) | AppliedPlan queries a previously applied upgrade plan by its name. | GET|/cosmos/upgrade/v1beta1/applied_plan/{name}|
-| `UpgradedConsensusState` | [QueryUpgradedConsensusStateRequest](#cosmos.upgrade.v1beta1.QueryUpgradedConsensusStateRequest) | [QueryUpgradedConsensusStateResponse](#cosmos.upgrade.v1beta1.QueryUpgradedConsensusStateResponse) | UpgradedConsensusState queries the consensus state that will serve as a trusted kernel for the next version of this chain. It will only be stored at the last height of this chain. UpgradedConsensusState RPC not supported with legacy querier | GET|/cosmos/upgrade/v1beta1/upgraded_consensus_state/{last_height}|
+| `UpgradedConsensusState` | [QueryUpgradedConsensusStateRequest](#cosmos.upgrade.v1beta1.QueryUpgradedConsensusStateRequest) | [QueryUpgradedConsensusStateResponse](#cosmos.upgrade.v1beta1.QueryUpgradedConsensusStateResponse) | UpgradedConsensusState queries the consensus state that will serve as a trusted kernel for the next version of this chain. It will only be stored at the last height of this chain. UpgradedConsensusState RPC not supported with legacy querier This rpc is deprecated now that IBC has its own replacement (https://github.com/cosmos/ibc-go/blob/2c880a22e9f9cc75f62b527ca94aa75ce1106001/proto/ibc/core/client/v1/query.proto#L54) | GET|/cosmos/upgrade/v1beta1/upgraded_consensus_state/{last_height}|
 | `ModuleVersions` | [QueryModuleVersionsRequest](#cosmos.upgrade.v1beta1.QueryModuleVersionsRequest) | [QueryModuleVersionsResponse](#cosmos.upgrade.v1beta1.QueryModuleVersionsResponse) | ModuleVersions queries the list of module versions from state. | GET|/cosmos/upgrade/v1beta1/module_versions|
 
  <!-- end services -->

proto/cosmos/upgrade/v1beta1/query.proto

@@ -23,7 +23,10 @@ service Query {
   // as a trusted kernel for the next version of this chain. It will only be
   // stored at the last height of this chain.
   // UpgradedConsensusState RPC not supported with legacy querier
+  // This rpc is deprecated now that IBC has its own replacement
+  // (https://github.com/cosmos/ibc-go/blob/2c880a22e9f9cc75f62b527ca94aa75ce1106001/proto/ibc/core/client/v1/query.proto#L54)
   rpc UpgradedConsensusState(QueryUpgradedConsensusStateRequest) returns (QueryUpgradedConsensusStateResponse) {
+    option deprecated            = true;
     option (google.api.http).get = "/cosmos/upgrade/v1beta1/upgraded_consensus_state/{last_height}";
   }
 
@@ -61,6 +64,8 @@ message QueryAppliedPlanResponse {
 // QueryUpgradedConsensusStateRequest is the request type for the Query/UpgradedConsensusState
 // RPC method.
 message QueryUpgradedConsensusStateRequest {
+  option deprecated = true;
+
   // last height of the current chain must be sent in request
   // as this is the height under which next consensus state is stored
   int64 last_height = 1;
@@ -69,6 +74,7 @@ message QueryUpgradedConsensusStateRequest {
 // QueryUpgradedConsensusStateResponse is the response type for the Query/UpgradedConsensusState
 // RPC method.
 message QueryUpgradedConsensusStateResponse {
+  option deprecated = true;
   reserved 1;
 
   bytes upgraded_consensus_state = 2;

x/upgrade/keeper/grpc_query.go

@@ -35,6 +35,7 @@ func (k Keeper) AppliedPlan(c context.Context, req *types.QueryAppliedPlanReques
 }
 
 // UpgradedConsensusState implements the Query/UpgradedConsensusState gRPC method
+// nolint: staticcheck
 func (k Keeper) UpgradedConsensusState(c context.Context, req *types.QueryUpgradedConsensusStateRequest) (*types.QueryUpgradedConsensusStateResponse, error) {
 	ctx := sdk.UnwrapSDKContext(c)