fix: Wrap alert and flash actions more responsively

[gethinwebster]

Description

Wrap alert and flash actions more responsively, based on actual content rather than breakpoints. This ensures they make the best use of the available space (not wrapping until smaller widths when content is small, and wrapping already at larger widths when content is longer).

Related links, issue #, if available: AWSUI-55633, AWSUI-60122

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 96.46%. Comparing base (a80c1cb) to head (d4b3ad9).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3338   +/-   ##
=======================================
  Coverage   96.46%   96.46%           
=======================================
  Files         805      805           
  Lines       23004    23019   +15     
  Branches     7960     7955    -5     
=======================================
+ Hits        22190    22205   +15     
- Misses        760      807   +47     
+ Partials       54        7   -47     

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[gethinwebster]

looking into this to see if it might cause problems with test utils cross-version compatibility

[gethinwebster]

(looks to be fine, no use of child combinators)