fix(menu): prevent scroll when navigating with arrow keys

[heloiselui]

Closes #19389

While working on the new Combo Button component for web-components #19218, @thyhmdo was reviewing the PR and noticed there was an unexpected scroll when navigating menu items using the up/down arrow keys. I investigated and found that the same behavior also occurs in the Menu Button.

Changelog

New

• Prevented unexpected scroll behavior when using ArrowUp or ArrowDown keys to navigate menu items by adding e.preventDefault() in the keyboard handler.

Testing / Reviewing

1. Go to Web Component Deploy Preview > Menu Button > Experimental Auto Align
2. Open the menu and use the up/down arrow keys to navigate through menu items
3. Expected: No scroll jump should occur during navigation

PR Checklist

As the author of this PR, before marking ready for review, confirm you:

• Reviewed every line of the diff
• [N/A] Updated documentation and storybook examples
• [N/A] Wrote passing tests that cover this change
• Addressed any impact on accessibility (a11y)
• Tested for cross-browser consistency
• Validated that this code is ready for review and status checks should pass

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.85%. Comparing base (9e05e6f) to head (7e01136).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #19392   +/-   ##
=======================================
  Coverage   84.85%   84.85%           
=======================================
  Files         371      371           
  Lines       14412    14412           
  Branches     4750     4694   -56     
=======================================
  Hits        12229    12229           
- Misses       2036     2037    +1     
+ Partials      147      146    -1     

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[ariellalgilmore]

LGTM!

[2nikhiltom]

LGTM, the ci checks needs some eyes