For #10395 - Improve alignment of close buttons with menu in tab tray

[darkwing]

Fixes #10395

Pull Request checklist

• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features. In addition, it includes a screenshot of a successful accessibility scan to ensure no new defects are added to the product.

After merge

• Milestone: Make sure issues finished by this pull request are added to the milestone of the version currently in development.

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[codecov-io]

Codecov Report

Merging #10405 into master will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master   #10405      +/-   ##
============================================
- Coverage     19.56%   19.53%   -0.04%     
  Complexity      601      601              
============================================
  Files           357      357              
  Lines         14396    14421      +25     
  Branches       1937     1940       +3     
============================================
  Hits           2817     2817              
- Misses        11323    11348      +25     
  Partials        256      256              

Impacted Files	Coverage Δ	Complexity Δ
.../mozilla/fenix/customtabs/CustomTabsIntegration.kt	0.00% <0.00%> (ø)	0.00% <0.00%> (ø%)

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[topotropic]

Thank you! LGTM