chore: Makes colorTextNotificationYellow themeable

[pan-kot]

Description

Rel: AWSUI-62156

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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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.60%. Comparing base (bcde582) to head (2c56578).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4752   +/-   ##
=======================================
  Coverage   97.60%   97.60%           
=======================================
  Files         951      951           
  Lines       30744    30744           
  Branches    11281    11281           
=======================================
  Hits        30007    30007           
  Misses        690      690           
  Partials       47       47           

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