fix 'Any language' choice in language selection menu

[osma]

Reasons for creating this PR

The "Any language" option in the content language selector was not working properly, probably because of changes caused by the Bootstrap 5 upgrade (#1182). When the user selected "Any language", the text changed to "undefined". This PR restores the original functionality.

Link to relevant issue(s), if any

• cleanup after Update to Bootstrap 5 #1182

Description of the changes in this PR

• use id="lang-button-all" instead of class="lang-button-all" because Bootstrap 5 seems to overwrite the class attribute but the id is preserved

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 #1315 (63a0dab) into master (712ead2) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1315   +/-   ##
=========================================
  Coverage     70.36%   70.36%           
  Complexity     1649     1649           
=========================================
  Files            32       32           
  Lines          3790     3790           
=========================================
  Hits           2667     2667           
  Misses         1123     1123           

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