fix: Make popover white-space style deterministic

[jperals]

Description

Ticket: AWSUI-60034

The same element had the CSS rule white-space: normal and white-space: nowrap with the same specificity, so the final style of the element couldn't be guaranteed. The specific order in which stylesheets are loaded can break the expected component appearance.

How has this been tested?

• Ran through my pipeline, no visual differences
• Checked with the browser dev tools that the CSS selector including the white-space: nowrap rule has higher specificity (1,2,0) than the one with the white-space: normal rule (1,1,0)

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 96.34%. Comparing base (ad36547) to head (5a47ddf).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3047   +/-   ##
=======================================
  Coverage   96.34%   96.34%           
=======================================
  Files         780      780           
  Lines       21927    21928    +1     
  Branches     7503     7513   +10     
=======================================
+ Hits        21126    21127    +1     
  Misses        749      749           
  Partials       52       52           

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[jperals]

I realized that these 3 rules were unnecessary because they are overriden by the typography.default-text-style mixin which is included further down