feat(runtime): avoid system exit and make health check service optional

[ndr-brt]

What this PR changes/adds

Makes runtime error finish with an exception.
Make HealthCheckService optional

Why it does that

Explained in #4060

Further notes

• made the BaseRuntimeFixture simpler by removing custom logic and dealing with mocking of ServiceLocator

Linked Issue(s)

Closes #4060

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 86.20690% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 74.52%. Comparing base (7f20ba5) to head (a804eee).
Report is 187 commits behind head on main.

Files	Patch %	Lines
...g/eclipse/edc/boot/system/runtime/BaseRuntime.java	90.47%	2 Missing ⚠️
...junit/extensions/DependencyInjectionExtension.java	0.00%	1 Missing ⚠️
...org/eclipse/edc/junit/extensions/EdcExtension.java	85.71%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4061      +/-   ##
==========================================
+ Coverage   71.74%   74.52%   +2.78%     
==========================================
  Files         919      976      +57     
  Lines       18457    19984    +1527     
  Branches     1037     1123      +86     
==========================================
+ Hits        13242    14894    +1652     
+ Misses       4756     4606     -150     
- Partials      459      484      +25     

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