[release-v0.38.x] de-dupe order and resource dependencies

[pritidesai]

Changes

This is a manual cherry-pick of #5446.

In case of a pipeline with a huge list of redundant dependencies, the list is growing exponentially. This way of calculating the list of dependencies is causing extra delay in the validation cycle. This delay sometimes hit the webhook timeout during validation. This is one of the changes being proposed to make the validation cycle efficient and avoid unnecessary delay.

/kind bug

Submitter Checklist

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Release Notes

De-dupe task dependencies - order and resource dependencies all together. It's very common to have a task with multiple when expressions referring to the same task but different results. Maintain a set of dependencies and add only a new parent.

[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/apis/pipeline/v1beta1/pipeline_types.go	96.8%	96.8%	-0.0
pkg/reconciler/pipelinerun/resources/pipelinerunstate.go	97.9%	97.8%	-0.1

[abayer]

/approve

[tekton-robot]

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[vdemeester]

/lgtm