chore: remove migrations 0.42 and below (cosmos#11556)

## Description

Removes migrations from 0.42 and below. 

---

### 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

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

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

@@ -152,6 +152,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (authz)[\#11060](https://github.com/cosmos/cosmos-sdk/pull/11060) `authz.NewMsgGrant` `expiration` is now a pointer. When `nil` is used then no expiration will be set (grant won't expire).
 * (x/distribution)[\#11457](https://github.com/cosmos/cosmos-sdk/pull/11457) Add amount field to `distr.MsgWithdrawDelegatorRewardResponse` and `distr.MsgWithdrawValidatorCommissionResponse`.
 * (x/auth/middleware) [#11413](https://github.com/cosmos/cosmos-sdk/pull/11413) Refactor tx middleware to be extensible on tx fee logic. Merged `MempoolFeeMiddleware` and `TxPriorityMiddleware` functionalities into `DeductFeeMiddleware`, make the logic extensible using the `TxFeeChecker` option, the current fee logic is preserved by the default `checkTxFeeWithValidatorMinGasPrices` implementation. Change `RejectExtensionOptionsMiddleware` to `NewExtensionOptionsMiddleware` which is extensible with the `ExtensionOptionChecker` option. Unpack the tx extension options `Any`s to interface `TxExtensionOptionI`.
+* (migrations) [#1156](https://github.com/cosmos/cosmos-sdk/pull/11556#issuecomment-1091385011) Remove migration code from 0.42 and below. To use previous migrations, checkout previous versions of the cosmos-sdk. 
 
 ### Client Breaking Changes