chore: Update one-theme button-link and alert styles

[at-susie]

Description

This PR 1) removes opacity from the alert background that caused accessibility color contrast issue when they are displayed on a gradient background, 2) updates button-link link component style for one-theme.

These changes make visual changes only for one-theme.

Related links, issue #, if available: n/a

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[at-susie]

Adding info here is an intentional general fix, not a one-theme regression.

.button overrides .variant-infos color in the CSS cascade regardless of theme. In visual-refresh, both tokens happen to resolve to the same blue, so the bug is invisible, but it's always there. Excluding info from applyButtonStyles is the correct fix.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.51%. Comparing base (b24a0ee) to head (02243b5).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4651   +/-   ##
=======================================
  Coverage   97.51%   97.51%           
=======================================
  Files         948      948           
  Lines       30361    30361           
  Branches    11073    11073           
=======================================
  Hits        29608    29608           
  Misses        746      746           
  Partials        7        7           

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