[backend/frontend] fix creator replaced by user in workbench (#6048)

[marieflorescontact]

Proposed changes

• frontend: add state in WorkbenchFileContent to to prevent useEffect from calling the saveFile() method each time content is loaded.
• backend: replace creator_id by the cerator_id as it is stored in DB instead of user.id

Related issues

• issue/6048

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.69%. Comparing base (79bc968) to head (11ecedb).
Report is 10 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6180   +/-   ##
=======================================
  Coverage   66.68%   66.69%           
=======================================
  Files         540      540           
  Lines       64349    64351    +2     
  Branches     5251     5253    +2     
=======================================
+ Hits        42909    42916    +7     
+ Misses      21440    21435    -5     

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