Remove endpoint's `SetChannelState`

[DimitrisJim]

To be removed https://github.com/cosmos/ibc-go/issues/3984 and replaced with usage of UpdateChannel. Looking at comment https://github.com/cosmos/ibc-go/issues/3984#issuecomment-1619786112 and bringing it up to current context, can deprecate now and remove in v10 but leaving this up for discussion.

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[crodriguezvega]

It's deprecated in v9, so we can remove in v11.