[stable31] fix(readonly-bar): Clean up read-only menu bar to behave consistently with normal menu bar

[backportbot]

Backport of #7560

Todo

• Review and resolve any conflicts
• Remove all the empty commits
• Amend HEAD commit to remove the line stating to skip CI

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Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.69%. Comparing base (75583e6) to head (a8fd4c7).
⚠️ Report is 4 commits behind head on stable31.

Additional details and impacted files

@@             Coverage Diff              @@
##           stable31    #7650      +/-   ##
============================================
+ Coverage     50.83%   57.69%   +6.86%     
============================================
  Files           292      291       -1     
  Lines         42056    37188    -4868     
  Branches        875      874       -1     
============================================
+ Hits          21378    21455      +77     
+ Misses        20557    15613    -4944     
+ Partials        121      120       -1     

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