refactor: make Services return Lists and not Streams

[ndr-brt]

What this PR changes/adds

Make services return collected Lists instead of Streams.

Why it does that

transactional context scope

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 #3682

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[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (0266575) 71.73% compared to head (734ffd7) 71.73%.
Report is 3 commits behind head on main.

Files	Patch %	Lines
...ontractagreement/ContractAgreementServiceImpl.java	71.42%	1 Missing and 1 partial ⚠️

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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3685   +/-   ##
=======================================
  Coverage   71.73%   71.73%           
=======================================
  Files         917      919    +2     
  Lines       18426    18465   +39     
  Branches     1041     1034    -7     
=======================================
+ Hits        13217    13246   +29     
- Misses       4750     4760   +10     
  Partials      459      459           

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