fix: fix validator unmarshal failed issue

[forcodedancing]

This pr fix an issue introduced in v0.10.12 release.

Issue:

panic: unmarshal to types.Validator failed after 160 bytes (insufficient bytes decoding []byte of length 1000000000000): 0A14666F9C66C385A14842F8730C4C906DAE8B22B9981214666F9C66C385A14842F8730C4C906DAE8B22B9981A251624DE64209142AFCC691B7CC05D26C7B0BE0C8B46418294171730E079F384FDE2FA50BAFC28023280A094A58D1D3A80A094A58D1D42090A07476168696E67614888E53C6A0E220C08D3F6DEF80510E1F4CA9A01721411896BEC37DAC5D41DC3FDB204DAFC0FCFC999A2920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D920180A094A58D1D9A0180C0DFDA8EE906

goroutine 386 [running]:
github.com/cosmos/cosmos-sdk/x/stake/types.MustUnmarshalValidator(_, {_, _, _})
	github.com/cosmos/[email protected]/x/stake/types/validator.go:145 +0x12e
github.com/cosmos/cosmos-sdk/x/stake/keeper.Keeper.GetValidator({{0x15f50a8, 0xc0004f5be0}, {0x15f50a8, 0xc0004f5bf0}, {0x15f50d0, 0xc0004f5c90}, 0xc000c62690, {0x161de88, 0xc0005ae0e0}, 0xc000bd6050, ...}, ...)
	github.com/cosmos/[email protected]/x/stake/keeper/validator.go:25 +0x191
github.com/cosmos/cosmos-sdk/x/stake/keeper.Keeper.GetValidatorByConsAddr({{0x15f50a8, 0xc0004f5be0}, {0x15f50a8, 0xc0004f5bf0}, {0x15f50d0, 0xc0004f5c90}, 0xc000c62690, {0x161de88, 0xc0005ae0e0}, 0xc000bd6050, ...}, ...)
	github.com/cosmos/[email protected]/x/stake/keeper/validator.go:44 +0x218
github.com/bnb-chain/node/app.(*ValAddrCache).GetDistributionAddr(_, {{0x1609b08, 0xc00013c020}, {0x16236b8, 0xc00bb70740}, {{0xa, 0x0, {}, {0x0, 0x0, ...}, ...}, ...}, ...}, ...)
	github.com/bnb-chain/node/app/fee_distribution.go:62 +0x150
github.com/bnb-chain/node/app.distributeFeeBEP159({{0x1609b08, 0xc00013c020}, {0x16236b8, 0xc00bb70740}, {{0xa, 0x0, {}, {0x0, 0x0, 0x0}, ...}, ...}, ...}, ...)
	github.com/bnb-chain/node/app/fee_distribution.go:83 +0x54a
github.com/bnb-chain/node/app.(*BinanceChain).EndBlocker(_, {{0x1609b08, 0xc00013c020}, {0x16236b8, 0xc00bb70740}, {{0xa, 0x0, {}, {0x0, 0x0, ...}, ...}, ...}, ...}, ...)
	github.com/bnb-chain/node/app/app.go:907 +0xc3e
github.com/cosmos/cosmos-sdk/baseapp.(*BaseApp).EndBlock(0xc000d005a0, {0x24fbf5e, {}, {0x0, 0x0, 0x0}, 0x0})
	github.com/cosmos/[email protected]/baseapp/baseapp.go:934 +0x1dd
github.com/cosmos/cosmos-sdk/server/concurrent.(*asyncLocalClient).EndBlockSync(0xc00069a2c0, {0x24fbf5e, {}, {0x0, 0x0, 0x0}, 0x0})
	github.com/cosmos/[email protected]/server/concurrent/async_local_client.go:408 +0x257
github.com/tendermint/tendermint/proxy.(*appConnConsensus).EndBlockSync(0xc01e067e00, {0x24fbf5e, {}, {0x0, 0x0, 0x0}, 0x0})
	github.com/tendermint/[email protected]/proxy/app_conn.go:115 +0x4e
github.com/tendermint/tendermint/state.execBlockOnProxyApp({0x160a550, 0xc000edce60}, {0x161a720, 0xc000e01df0}, 0xc005d5b2c0, 0x14, {0x1625fb8, 0xc0006124c8})
	github.com/tendermint/[email protected]/state/execution.go:298 +0x5f0
github.com/tendermint/tendermint/state.(*BlockExecutor).ApplyBlock(_, {{{0xa, 0x0}, {0xc00a8dbe90, 0x6}}, {0xc000134978, 0x14}, 0x24fbf5d, 0x1f1600, {{0xc01d8fbde0, ...}, ...}, ...}, ...)
	github.com/tendermint/[email protected]/state/execution.go:128 +0x17b
github.com/tendermint/tendermint/blockchain/v0.(*BlockchainReactor).poolRoutine(0xc001383a00)
	github.com/tendermint/[email protected]/blockchain/v0/reactor.go:401 +0xcfb
created by github.com/tendermint/tendermint/blockchain/v0.(*BlockchainReactor).SwitchToBlockchain
	github.com/tendermint/[email protected]/blockchain/v0/reactor.go:154 +0x2e6