The admin reskin changed info notices to a transparent background, matching usage in Gutenberg. But with the gray background in the core admin, these notices didn't show up in an expected manner. Additionally, using a transparent background in a context where the background color is variable is risky for color contrast.
Change `.notice-info`, `.notice-info.notice-alt`, and `.login .notice, .login .message` to use white backgrounds. Reverts changes from [61731] to apply styles also to `.message` class.
Props mohitbsf, audrasjb, peterwilsoncc, pbiron, fabiankaegy, noruzzaman, joedolson.
Fixes#64678. See #64715.
Built from https://develop.svn.wordpress.org/trunk@61737
git-svn-id: http://core.svn.wordpress.org/trunk@61043 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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