fix(diff): improve server-side diff detection for custom resources

[sujay2306]

Description

This PR fixes an issue where server-side diff in Argo CD fails to detect changes in custom resources when fields are added or removed. Specifically, it addresses the problem where removing the autoRestart field from a KafkaConnector resource wasn't being detected as a change.

Changes

1. Modified the diffArrayCached function in util/argo/diff/diff.go to handle custom resources properly:
   • Added detection for custom resources by comparing API versions
   • Forces diff calculation for custom resources instead of using cached results
   • Maintains caching behavior for non-custom resources

Impact

• Proper detection of field-level changes (additions/removals) in custom resources
• Maintains performance benefits of caching for non-custom resources
• Ensures accurate diff detection when modifying fields like autoRestart in KafkaConnector

Testing

• Added test case for KafkaConnector field removal detection
• Verified that other custom resource field changes are detected correctly
• Ensured non-custom resources still benefit from caching

Related Issues

#23127
Closes #23127

Documentation

• No additional documentation changes required as this is a bug fix

Checklist

• I've created an enhancement proposal and discussed it with the community
• The title of the PR states what changed and the related issues number
• I've updated both the CLI and UI to expose my feature
• I have signed off all my commits as required by DCO
• I have written unit and e2e tests for my change
• My build is green
• I have added a brief description of why this PR is necessary

[bunnyshell]

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[blakepettersson]

Hasn't this been fixed with #23066? Can you verify if running a build from master still has the initial issue or not?

[codecov]

Codecov Report

❌ Patch coverage is 78.57143% with 3 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@0484f9f). Learn more about missing BASE report.
⚠️ Report is 428 commits behind head on master.

Files with missing lines	Patch %	Lines
util/argo/diff/diff.go	78.57%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #23128   +/-   ##
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  Coverage          ?   60.04%           
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  Files             ?      343           
  Lines             ?    57896           
  Branches          ?        0           
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  Hits              ?    34763           
  Misses            ?    20362           
  Partials          ?     2771           

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