[BUGFIX] argilla server: Prevent convert ChatFieldValue objects

[frascuchon]

Description

Changes introduced in #5600 include a but when the fields in the RecordCreate schema already contain ChatFieldValue object. This is the cause of failing integration tests in the develop branch.

The custom validator must skip these objects even if the pre flag is set to True.

This PR fixes the error.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested

Checklist

• I added relevant documentation
• I followed the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• I confirm My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.23%. Comparing base (de153ea) to head (59a8e39).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5605      +/-   ##
===========================================
+ Coverage    91.21%   91.23%   +0.01%     
===========================================
  Files          145      145              
  Lines         6036     6036              
===========================================
+ Hits          5506     5507       +1     
+ Misses         530      529       -1     

Flag	Coverage Δ
argilla-server	91.23% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[jfcalvo]

🙈