Fix feedback form limit php81 deprecation warning

[osma]

Reasons for creating this PR

Follow-up fix to PR #1566 to address PHP 8.1 deprecation warnings. That PR used substr for truncation in a way that could trigger deprecation warnings when null values were encountered. This PR instead adds a maxlimit parameter to the Request.getQueryParamPOST method and uses that instead of plain substr, avoiding the problem.

Link to relevant issue(s), if any

• follow-up to Length limits for feedback form #1566

Description of the changes in this PR

• support maxlimit parameter in Request.getQueryParamPOST
• add unit tests to verify above
• switch WebController to use getQueryParamPost with maxlimit instead of plain substr

Known problems or uncertainties in this PR

n/a

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (3b9489a) 70.22% compared to head (46ea133) 70.32%.

Files	Patch %	Lines
controller/WebController.php	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1567      +/-   ##
============================================
+ Coverage     70.22%   70.32%   +0.10%     
- Complexity     1665     1667       +2     
============================================
  Files            32       32              
  Lines          4295     4300       +5     
============================================
+ Hits           3016     3024       +8     
+ Misses         1279     1276       -3     

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
3 Code Smells

No Coverage information
0.0% Duplication