Set consistent margin-bottom for .wp-filter in list-tables.css

[shazzad]

Set the plugins tab bottom margin to 1rem, matching the old description margin.

Trac ticket: https://core.trac.wordpress.org/ticket/64337

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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Props sajib1223.

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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: 61353
GitHub commit: 2929fe2

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