[backend] fix: add orphanRomoval parameter for Scenarion/inject relat…

[heditar]

Proposed changes

• Spring upgrade created a bug that was throwing an error while trying to delete a scenario/simulation. This PR fix this issue by adding cascade = CascadeType.REMOVE to the relationship

Testing Instructions

1. Create a scenario/simulation, add an inject, delete ii -> it should succeed

Related issues

• Closes #5

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case
• [NA] I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality
• For bug fix -> I implemented a test that covers the bug

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.50%. Comparing base (7e088a9) to head (a16f947).
⚠️ Report is 1 commits behind head on release/current.

Additional details and impacted files

@@                Coverage Diff                 @@
##             release/current    #4968   +/-   ##
==================================================
  Coverage              59.49%   59.50%           
- Complexity              5091     5094    +3     
==================================================
  Files                   1039     1039           
  Lines                  31740    31740           
  Branches                2372     2372           
==================================================
+ Hits                   18885    18888    +3     
  Misses                 11796    11796           
+ Partials                1059     1056    -3     

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[GaetanSantucci]

Test ok, corresponds to the expected behavior