refactor(test): speed up e2e tests

[ndr-brt]

What this PR changes/adds

Export classpath loading from EmbeddedRuntime

Why it does that

Classpath loading is a time consuming operation (approx 14 seconds first time it runs, 4-5 seconds other times) as it needs to invoke gradle wrapper and the printClasspath task. By doing it just once for every runtime in the e2e-transfer-test makes tests run faster (approx 1 minute less than before)

Further notes

List other areas of code that have changed but are not necessarily linked to the main feature. This could be method
signature changes, package declarations, bugs that were encountered and were fixed inline, etc.

Linked Issue(s)

Closes # <-- insert Issue number if one exists

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 33 lines in your changes missing coverage. Please review.

Project coverage is 75.16%. Comparing base (7f20ba5) to head (1b63226).
Report is 325 commits behind head on main.

Files	Patch %	Lines
.../eclipse/edc/junit/extensions/ClasspathReader.java	0.00%	27 Missing ⚠️
.../eclipse/edc/junit/extensions/EmbeddedRuntime.java	0.00%	6 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4302      +/-   ##
==========================================
+ Coverage   71.74%   75.16%   +3.42%     
==========================================
  Files         919     1052     +133     
  Lines       18457    21094    +2637     
  Branches     1037     1180     +143     
==========================================
+ Hits        13242    15856    +2614     
+ Misses       4756     4724      -32     
- Partials      459      514      +55     

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[paullatzelsperger]

i'm wondering: the improvement consists of not doing the CP scanning in the boot() method, but in the constructor, right? so it would only come into play when the runtime is initialized on every method, but not on every class, correct?

[ndr-brt]

i'm wondering: the improvement consists of not doing the CP scanning in the boot() method, but in the constructor, right? so it would only come into play when the runtime is initialized on every method, but not on every class, right?

the advantage kicks in also in the "runtime per class" case, e.g. in the "e2e transfer tests" where a single runtime is used multiple time across different tests (see backend-service runtime, used in 7 different test classes). Loading its classpath once will make things faster.

[paullatzelsperger]

the advantage kicks in also in the "runtime per class" case, e.g. in the "e2e transfer tests" where a single runtime is used multiple time across different tests (see backend-service runtime, used in 7 different test classes).

true. seriously cool shit!!