refactor: Simplify delete value pre-checks

[seakayone]

• move auth logic into auth service
• simplify

Description

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 16 lines in your changes missing coverage. Please review.

Project coverage is 20.89%. Comparing base (6ebe8e7) to head (649ee0b).
Report is 223 commits behind head on main.

Files with missing lines	Patch %	Lines
...knora/webapi/responders/v2/ValuesResponderV2.scala	0.00%	13 Missing ⚠️
...pi/slice/common/api/AuthorizationRestService.scala	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3524       +/-   ##
===========================================
- Coverage   83.04%   20.89%   -62.16%     
===========================================
  Files         290      317       +27     
  Lines       23087    22531      -556     
===========================================
- Hits        19172     4707    -14465     
- Misses       3915    17824    +13909     

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