chore: reset cache on pool creation (backport #8415)

[mergify[bot]]

Closes: #XXX

What is the purpose of the change

Resets cache on pool creation.

Testing and Verifying

(Please pick one of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added unit test that validates ...
• Added integration tests for end-to-end deployment with ...
• Extended integration test for ...
• Manually verified the change by ...

Documentation and Release Note

• [ ] Does this pull request introduce a new feature or user-facing behavior changes?
• [ ] Changelog entry added to Unreleased section of CHANGELOG.md?

Where is the change documented?

• [ ] Specification (x/{module}/README.md)
• [ ] Osmosis documentation site
• [ ] Code comments?
• [ ] N/A

  ---

  This is an automatic backport of pull request #8415 done by Mergify.

[mergify[bot]]

Cherry-pick of c69482a66c6639e8234df14475eef725e9b3fe91 has failed:

On branch mergify/bp/v25.x/pr-8415
Your branch is up to date with 'origin/v25.x'.

You are currently cherry-picking commit c69482a6.
  (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/poolmanager/create_pool.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/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally