refactor: Remove MessageRelay from Value Responder

[BalduinLandolt]

Pull Request Checklist

Task Description/Number

Issue Number: DEV-

PR Type

• build/chore: maintenance tasks (no production code change)
• docs: documentation changes (no production code change)
• feat: represents new features
• fix: represents bug fixes
• perf: performance improvements
• refactor: represents production code refactoring
• test: adding or refactoring tests (no production code change)
• deprecated: Deprecation warning (ideally referencing a migration guide)

Basic requirements for bug fixes and features

• Tests for the changes have been added
• Docs have been added / updated

Does this PR introduce a breaking change?

• Yes

[codecov]

Codecov Report

Attention: Patch coverage is 95.23810% with 4 lines in your changes missing coverage. Please review.

Project coverage is 83.59%. Comparing base (a622e4f) to head (d902c15).
Report is 89 commits behind head on main.

Files	Patch %	Lines
...knora/webapi/responders/v2/ValuesResponderV2.scala	84.61%	2 Missing ⚠️
...ponders/v2/resources/CreateResourceV2Handler.scala	97.18%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3268       +/-   ##
===========================================
+ Coverage   13.22%   83.59%   +70.37%     
===========================================
  Files         270      281       +11     
  Lines       22244    22934      +690     
===========================================
+ Hits         2941    19172    +16231     
+ Misses      19303     3762    -15541     

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[siers]

Nice!