[release-v0.56.x] Cleanup resolved object before validating through dry-run

[vdemeester]

Changes

Cherry picked fro #8051

This ensure that we are not going to fail during validation with
dry-run. An example of such a failure would be the following scenario.

• A task in a namespace has ownerReferences with
  blockOwnerDeletion: true
• A user uses the cluster resolver to fetch that task
• That user doesn't have a lot of rights in that namespace (only
  listing Tasks for example).

/kind bug

Signed-off-by: Vincent Demeester vdemeest@redhat.com

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• Has Docs if any changes are user facing, including updates to minimum requirements e.g. Kubernetes version bumps
• Has Tests included if any functionality added or changed
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Release Notes

Cleanup resolved object before attempting to validate it through api dry-run call

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/reconciler/pipelinerun/resources/pipelineref.go	94.3%	93.5%	-0.9
pkg/reconciler/taskrun/resources/taskref.go	94.2%	92.9%	-1.3

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage-df to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/reconciler/pipelinerun/resources/pipelineref.go	94.3%	93.5%	-0.9
pkg/reconciler/taskrun/resources/taskref.go	94.2%	92.9%	-1.3

[vdemeester]

/retest

[chitrangpatel]

/retest

[chitrangpatel]

/retest

[chitrangpatel]

/approve
/lgtm

[tekton-robot]

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