Remove x/group from required dependency

[julienrbrt]

Currently x/group is imported in the main testing/simapp: https://github.com/cosmos/ibc-go/blob/main/testing/simapp/app.go#L69

It would be cool to get this removed given that it is deprecated: https://github.com/cosmos/cosmos-sdk/tree/main/x#deprecated-modules (some lean forks may want to remove that module, without needing to fork IBC).

[linear]

IBCGO-2376 Remove x/group from required dependency

[anhductn2001]

Can I handle it? @julienrbrt