Update codeowners entries for TW team

What does this MR do and why?

We've run into some edge cases where no one on the TW was able to approve changes to certain docs files. After some testing and discussion, we'd like to add a few more entries to try to close these gaps. See the related issue for more details.

The main changes:

• Change @susantacker @dianalogan @kpaizee @sselhorn to @gitlab-org/tw-leadership, the new group we created specifically to make this easier to manage.
• Add @gitlab-org/tw-leadership to the top-level * rule, so that if we run into different edge cases in the future, someone in TW leadership will be able to approve the MR if needed.
• Add 5 new entries into the top level section for documentation linting and config files that we think should have approvals as required (not optional). Set as required by adding them to the top level and adding the TW team DRI's for those files.
• Add /data/deprecations/ and /data/removals/ with a DRI of @gl-docsteam to the optional [Documentation Directories] section, because it wasn't always clear to deprecations/removals authors that the TW team should be the ones approving those.

Related to #374084 (closed)

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