Copy message before passing it to eventtype autocreate handler

[creydr]

Currently we see the TestEventTransformationForTriggerV1BrokerV1 e2e test failing, when the eventtype-auto-create FF is enabled. This is because we're not copying the message at the right place.

From the docs:

CopyMessage reads m once and creates an in-memory copy depending on the encoding of m. The returned copy is not dependent on any transport and can be visited many times. When the copy can be forgot, the copied message must be finished with Finish() message to release the memory. transformers can be nil and this function guarantees that they are invoked only once during the encoding process

This means, that m gets read by buffering.CopyMessage() and thus is "used" for further usages.

/cherry-pick release-1.14

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 69.51%. Comparing base (7e1c082) to head (92b0dc4).
Report is 55 commits behind head on main.

Files	Patch %	Lines
pkg/kncloudevents/event_dispatcher.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7934      +/-   ##
==========================================
+ Coverage   69.22%   69.51%   +0.29%     
==========================================
  Files         339      344       +5     
  Lines       19494    15994    -3500     
==========================================
- Hits        13494    11119    -2375     
+ Misses       5337     4189    -1148     
- Partials      663      686      +23     

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[creydr]

/cc @Cali0707

[Cali0707]

/lgtm

Thanks for catching this @creydr !

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Cali0707, creydr

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[creydr]

/cherry-pick release-1.14

[knative-prow-robot]

@creydr: new pull request created: #7937

In response to this:

/cherry-pick release-1.14

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[pierDipi]

@creydr it would be great to get a regression test for this

[creydr]

@creydr it would be great to get a regression test for this

I see 2 options:

1. Adding a dedicated test to the experimental suite which tests one flow (something from the rekt test suite)
2. Or enabling the eventtype-auto-create FF for the reconciler test suite (not sure if we are "ready" for this yet though)

Objections @pierDipi?

[Cali0707]

Or enabling the eventtype-auto-create FF for the reconciler test suite (not sure if we are "ready" for this yet though)

@creydr we already do this option in EKB, maybe it makes sense here as well?