Upgrade/Install: Add files removed in 7.0 to $_old_files

[ellatrix]

https://core.trac.wordpress.org/ticket/65273

[github-actions]

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Core Committers: Use this line as a base for the props when committing in SVN:

Props ellatrix.

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[github-actions]

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[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 62383
GitHub commit: 2acdbd6

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.