Prevent generation only updates

[pierDipi]

This guards and discard contract ConfigMap updates when only generation
changes.

While this approach is technically slightly slower, the latency is negligible,
and it is more robust and easier to maintain.

Proposed Changes

• guards and discard contract ConfigMap updates when only generation
  changes
• move change detection to the shared library

Release Note

Prevent unnecessary ConfigMap updates and reduce API server load

Docs

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pierDipi

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[codecov]

Codecov Report

Attention: Patch coverage is 44.70588% with 47 lines in your changes are missing coverage. Please review.

Project coverage is 49.24%. Comparing base (97732b7) to head (9b4d7e0).
Report is 1 commits behind head on main.

Files	Patch %	Lines
control-plane/pkg/reconciler/trigger/trigger.go	16.66%	7 Missing and 3 partials ⚠️
control-plane/pkg/reconciler/channel/channel.go	60.00%	6 Missing and 2 partials ⚠️
control-plane/pkg/reconciler/broker/broker.go	36.36%	5 Missing and 2 partials ⚠️
control-plane/pkg/reconciler/sink/kafka_sink.go	30.00%	5 Missing and 2 partials ⚠️
...ntrol-plane/pkg/reconciler/channel/v2/channelv2.go	28.57%	4 Missing and 1 partial ⚠️
control-plane/pkg/reconciler/consumer/consumer.go	54.54%	3 Missing and 2 partials ⚠️
control-plane/pkg/reconciler/base/reconciler.go	62.50%	2 Missing and 1 partial ⚠️
control-plane/pkg/contract/extensions.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3915      +/-   ##
============================================
- Coverage     53.59%   49.24%   -4.36%     
============================================
  Files           344      247      -97     
  Lines         18346    14925    -3421     
  Branches        294        0     -294     
============================================
- Hits           9833     7350    -2483     
+ Misses         7575     6816     -759     
+ Partials        938      759     -179     

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[pierDipi]

This is because the test wants to test "no operations" and without an annotation now the control plane will set the annotation on the data plane pod so that the CM and the annotation is fully consistent

[creydr]

/lgtm

[creydr]

Putting on hold in case you want some other reviews too
/hold

Feel free to unhold

[mgencur]

I'm not an expert here but it looks good.