Validate beta features for inline pipelines and tasks

[lbernick]

Prior to this commit, validation of beta features was performed for v1 referenced Tasks and Pipelines (both local and remote), but not v1 inline Tasks and Pipelines.

This commit ensures that beta feature validation is the same for both inline and referenced Tasks and Pipelines.

/kind bug

Closes #7077

Submitter Checklist

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Release Notes

Bug fix: validate beta features in inline tasks/pipelines in the same way as referenced tasks/pipelines

[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/v1/pipelinerun_validation.go	94.0%	94.0%	0.0
pkg/apis/pipeline/v1/taskrun_validation.go	97.7%	97.8%	0.0

[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/apis/pipeline/v1/pipelinerun_validation.go	94.0%	94.0%	0.0
pkg/apis/pipeline/v1/taskrun_validation.go	97.7%	97.8%	0.0

[JeromeJu]

/lgtm

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JeromeJu, vdemeester

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[JeromeJu]

Redirecting the discussion at #7077 (comment) on whether we would want to backport this:
I think we might need to decide whether to backport this or not? From my understanding, it is good practice to backport while the reason for not backporting this one specifically is that the changes could be breaking users who choose to use enable-api-fields=stable and are using beta features in the past, which is similar to the decouple api and feature versioning change.

[lbernick]

I'd be in favor of backporting, since this is a bug fix that restores behavior prior to 0.49.
/cherry-pick release-v0.50.x

[tekton-robot]

@lbernick: new pull request created: #7080

In response to this:

I'd be in favor of backporting, since this is a bug fix that restores behavior prior to 0.49.
/cherry-pick release-v0.50.x

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