Correct behavior under LegacyVersion when deprecation warnings are enabled.

[jaraco]

• Remove suppression of deprecation warning for LegacyVersion. Ref [BUG] import pkg_resources emits DeprecationWarning #2885.
• Fix sorting of filenames not to rely on LegacyVersion. Fixes [BUG] import pkg_resources emits DeprecationWarning #2885.
• Replace invalid local version with a valid form.
• Update config.ConfigMetadataHandler._parse_version not to rely on LegacyVersion.
• Suppress invalid versions when parsing in package_index. They will still be allowed for now as long as DeprecationWarnings aren't treated as errors.

Summary of changes

Closes

Pull Request Checklist

• Changes have tests
• News fragment added in changelog.d/.
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