Reject dynakubes that use public image and not read only oneAgents

[waodim]

Description

Ticket

Previously when a dynakube was applied that had a mode that does not use read only oneagents (so everything that is not cloudNative or hostMon with csi) and a custom image (which we interpret as public images) then the oneAgent pods would run into a CrashLoopBackOff error.

In the pods you'd find this message:

❯ k logs daemonsets/cfg-oneagent
Found 3 pods, using pod/cfg-oneagent-2ghqj
[2025-01-22 13:41:58.584 UTC] [000a1650] [info   ] [bootstrapper] Started agent deployment as a container, PID 661072
[2025-01-22 13:41:58.586 UTC] [000a1650] [error  ] [bootstrapper] Volume storage should be mounted on /mnt/volume_storage_mount with write permissions

With this PR this configuration is now rejected in the first place.

How can this be tested?

Try those modes in combination with a custom image

example:

helm install dynatrace-operator -n dynatrace oci://public.ecr.aws/dynatrace/dynatrace-operator --version 1.4.0 -n dynatrace --set csidriver.enabled=false

spec:
  oneAgent:
    hostMonitoring:
      image: public.ecr.aws/dynatrace/dynatrace-oneagent:1.305.98.20250114-172617

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.19%. Comparing base (beb5e16) to head (0d4fc87).
Report is 4 commits behind head on release-1.4.

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Additional details and impacted files

@@             Coverage Diff              @@
##           release-1.4    #4346   +/-   ##
============================================
  Coverage        64.18%   64.19%           
============================================
  Files              401      401           
  Lines            26972    26977    +5     
============================================
+ Hits             17312    17317    +5     
  Misses            8293     8293           
  Partials          1367     1367           

Flag	Coverage Δ
unittests	64.19% <100.00%> (+<0.01%)	⬆️

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