refactor: clean up keeper interfaces (backport #2394)

[mergify]

This is an automatic backport of pull request #2394 done by Mergify.
Cherry-pick of 1313b63 has failed:

On branch mergify/bp/v11.x/pr-2394
Your branch is up to date with 'origin/v11.x'.

You are currently cherry-picking commit 1313b635.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   x/gamm/keeper/keeper.go
	modified:   x/gamm/keeper/pool_service.go
	modified:   x/gamm/types/expected_keepers.go
	modified:   x/incentives/types/expected_keepers.go
	modified:   x/lockup/keeper/keeper.go
	modified:   x/lockup/keeper/lock.go
	modified:   x/lockup/types/expected_keepers.go
	modified:   x/mint/keeper/keeper.go
	modified:   x/mint/types/expected_keepers.go
	modified:   x/pool-incentives/types/expected_keepers.go
	modified:   x/superfluid/keeper/epoch.go
	modified:   x/superfluid/keeper/keeper.go
	modified:   x/superfluid/types/expected_keepers.go
	modified:   x/tokenfactory/types/expected_keepers.go
	modified:   x/txfees/keeper/keeper.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CHANGELOG.md
	both modified:   app/keepers/keepers.go
	both modified:   x/incentives/keeper/gauge.go
	both modified:   x/incentives/keeper/keeper.go
	both modified:   x/txfees/types/expected_keepers.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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