[backport -> release/3.7.x] fix(migrations): split redis migrations into up and teardown

[team-gateway-bot]

Automated backport to release/3.7.x, triggered by a label in #12983.

Original description

Summary

"UP" phase should only contain non-destructive operations. "TEARDOWN" (or "FINISH") phase should be used to change/delete data.

Checklist

• [x] The Pull Request has tests
• [x] A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• [x] N/A ~~There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE~~

Issue reference

KAG-4419 https://github.com/Kong/kong/issues/12978