fix: adding value length check for full name field

[cmltaWt0]

Description

Fixing an error when a new user tries registering on the platform with a full name longer than 255 characters.

Now the request to the backend will not be sent because validation fails:

I also created a MR#34577 to Platform so that the backend would not miss such errors. But validation on the backend is just a fuse. It’s better not to send an invalid request to the backend.

It's a recreation of #1242

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.59%. Comparing base (a615cba) to head (8bdc0bb).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1561      +/-   ##
==========================================
+ Coverage   87.58%   87.59%   +0.01%     
==========================================
  Files         124      124              
  Lines        2303     2305       +2     
  Branches      643      648       +5     
==========================================
+ Hits         2017     2019       +2     
  Misses        277      277              
  Partials        9        9              

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