chore: remove legacy migrations

CHANGELOG.md

@@ -43,6 +43,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking
 
+* (core) [\#2897](https://github.com/cosmos/ibc-go/pull/2897) Remove legacy migrations required for upgrading from Stargate release line to ibc-go >= v1.x.x.
 * (core/02-client) [\#2856](https://github.com/cosmos/ibc-go/pull/2856) Rename `IterateClients` to `IterateClientStates`. The function now takes a prefix argument which may be used for prefix iteration over the client store.
 * (apps/27-interchain-accounts) [\#2607](https://github.com/cosmos/ibc-go/pull/2607) `SerializeCosmosTx` now takes in a `[]proto.Message` instead of `[]sdk.Msg`.
 * (apps/transfer) [\#2446](https://github.com/cosmos/ibc-go/pull/2446) Remove `SendTransfer` function in favor of a private `sendTransfer` function. All IBC transfers must be initiated with `MsgTransfer`.

modules/core/02-client/keeper/migrations.go

@@ -3,7 +3,6 @@ package keeper
 import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 
-	v100 "github.com/cosmos/ibc-go/v6/modules/core/02-client/legacy/v100"
 	v7 "github.com/cosmos/ibc-go/v6/modules/core/02-client/migrations/v7"
 )
 
@@ -17,16 +16,6 @@ func NewMigrator(keeper Keeper) Migrator {
 	return Migrator{keeper: keeper}
 }
 
-// Migrate1to2 migrates from version 1 to 2.
-// This migration
-// - migrates solo machine client states from v1 to v2 protobuf definition
-// - prunes solo machine consensus states
-// - prunes expired tendermint consensus states
-// - adds iteration and processed height keys for unexpired tendermint consensus states
-func (m Migrator) Migrate1to2(ctx sdk.Context) error {
-	return v100.MigrateStore(ctx, m.keeper.storeKey, m.keeper.cdc)
-}
-
 // Migrate2to3 migrates from version 2 to 3.
 // This migration
 // - migrates solo machine client states from v2 to v3 protobuf definition