fix(x/twap): incorrect time delta due to nanoseconds in time (backport #4359)

[mergify]

This is an automatic backport of pull request #4359 done by Mergify.
Cherry-pick of f56280f has failed:

On branch mergify/bp/v15.x/pr-4359
Your branch is up to date with 'origin/v15.x'.

You are currently cherry-picking commit f56280f4.
  (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:   tests/e2e/e2e_test.go
	modified:   x/twap/keeper_test.go
	modified:   x/twap/logic.go
	modified:   x/twap/logic_test.go
	modified:   x/twap/strategy.go
	modified:   x/twap/strategy_test.go
	modified:   x/twap/types/utils.go
	modified:   x/twap/types/utils_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CHANGELOG.md

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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