Remove generated CSS alts in dashicons.css

[joedolson]

This will prevent plugins and themes that require dashicons.css from breaking support for older Safari versions.

For clarity, this does not resolve the issue reported in the related ticket; core menu icons will still be missing in unsupported Safari browsers. But it will prevent this issue from expanding to 3rd party applications that require dashicons.css as a dependency.

Trac ticket: https://core.trac.wordpress.org/ticket/64266

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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 joedolson.

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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: 61290
GitHub commit: f9e9f59

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