[backend] Using parallel stream to execute injects

[Dimfacion]

Proposed changes

• Changing the job of inject execution to make use of parallelism

Testing Instructions

1. Create a simulation with a lot of injects launching at the same time
2. Launch it
3. It should start them all at the same time

Related issues

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
• For bug fix -> I implemented a test that covers the bug

[codecov]

Codecov Report

Attention: Patch coverage is 14.28571% with 12 lines in your changes missing coverage. Please review.

Project coverage is 41.41%. Comparing base (5c0a870) to head (bc995a0).
Report is 3 commits behind head on release/current.

Files with missing lines	Patch %	Lines
...io/openbas/scheduler/jobs/InjectsExecutionJob.java	14.28%	12 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##             release/current    #3129   +/-   ##
==================================================
  Coverage              41.40%   41.41%           
  Complexity              2346     2346           
==================================================
  Files                    693      693           
  Lines                  21292    21294    +2     
  Branches                1453     1453           
==================================================
+ Hits                    8817     8818    +1     
- Misses                 11978    11979    +1     
  Partials                 497      497           

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