Fix overlapping titles in wiki sidebar navigation

What does this MR do and why?

This MR backports Revert "Merge branch 'fix-item-height-in-wiki-s... (!124869 - merged) and Set a min-height for wiki list items (!124985 - merged) to %16.0 for inclusion in the patch release.

Fixing the height of Wiki sidebar components without implementing any further styling (i.e. word breaks, whitespace, text-overflow) leads to significant navigation issues with overlapping page titles. See Wiki titles on the sidebar overlap if they reac... (#412894 - closed).

This MR introduces min-height instead of an absolute height. This keeps the solution for the original problem of buttons overrunning the height of the list-item, without setting a fixed width that causes navigation to break for titles longer than 1 line.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:package-and-test-ee job has either succeeded or been approved by a Software Engineer in Test.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).