[backend] fix constraint on delete set null to cascade

[savacano28]

Proposed changes

• Modify constraint on delete for inject importers ans rule attributs

Related issues

• After modification on injectorService l77, when we make a deletebyId, I found a fk error :
  

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 32.58%. Comparing base (ee7f6df) to head (8c85969).
Report is 10 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1532      +/-   ##
============================================
+ Coverage     32.53%   32.58%   +0.04%     
- Complexity     1464     1466       +2     
============================================
  Files           534      535       +1     
  Lines         13777    13787      +10     
  Branches        824      824              
============================================
+ Hits           4482     4492      +10     
  Misses         9086     9086              
  Partials        209      209              

Flag	Coverage Δ
	32.58% <100.00%> (+0.04%)	⬆️

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