The measurement in px for zero values is not needed. It does this for Twenty Twenty-One, Twenty Ten, Twenty Eleven and Twenty Nineteen. This also adds short-hand-property-no-redudant-values to Twenty Twenty-One's stylelint rules. Included is removing box-shadow prefixed rules before the standard property in Twenty Ten. Finally, it also removes empty spaces at the ends of lines in Twenty Thirteen, Twenty Nineteen and Twenty Twenty.
Props ankitmaru, SergeyBiryukov, netweb, mukesh27, ryelle, audrasjb, sabernhardt.
Fixes#53874.
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