minor CSS tweaks after Bootstrap 5 update

[osma]

Reasons for creating this PR

Fix some minor layout issues found after the Bootstrap 5 update (PR #1182) by @kinow .

Link to relevant issue(s), if any

• cleanup after Update to Bootstrap 5 #1182

Description of the changes in this PR

• adjust text size for the language selection (dropdown style selector)
• make sure the "from all vocabularies" choice wraps so part of the text is not obscured
• decrease the size of the placeholder text on the feedback form
• tweak the vertical alignment of the copy to clipboard icon to make @MikkoAleksanteri happy

Known problems or uncertainties in this PR

n/a

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if not, explain why below)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #1321 (8ce0bc1) into master (566ad4b) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1321   +/-   ##
=========================================
  Coverage     70.68%   70.68%           
  Complexity     1646     1646           
=========================================
  Files            32       32           
  Lines          3786     3786           
=========================================
  Hits           2676     2676           
  Misses         1110     1110           

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[joelit]

As far as I could follow the differences in my browser (Chromium), looks fine to me.

Although I noticed a bug while testing, that just shows there's still tweaking to do with the new Bootstrap: