PMM-13579 Fix truncate of queries.

[BupycHuk]

PMM-13579

Link to the Feature Build: SUBMODULES-3806

If this PR adds or removes or alters one or more API endpoints, please review and add or update the relevant API documents as well:

• API Docs updated

If this PR is related to some other PRs in this or other repositories, please provide links to those PRs:

• Links to related pull requests (optional).

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 43.55%. Comparing base (b7885f1) to head (1f2694d).

Files with missing lines	Patch %	Lines
...ents/postgres/pgstatstatements/pgstatstatements.go	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##               v3    #3419      +/-   ##
==========================================
- Coverage   43.57%   43.55%   -0.02%     
==========================================
  Files         366      366              
  Lines       44238    44242       +4     
==========================================
- Hits        19275    19270       -5     
- Misses      23275    23284       +9     
  Partials     1688     1688              

Flag	Coverage Δ
agent	51.90% <85.71%> (-0.07%)	⬇️

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