cleaning up label keys 🧹

[pritidesai]

Changes

We have defined GroupName as a constant which is set to tekon.dev in register.go. We have other label keys defined in the same go file which are used by the controller to set the appropriate labels. These keys are TaskLabelKey, PipelineLabelKey, etc. These keys are set to "/task", "/pipeline", etc. Now while adding such labels in the Tekton
resources, we join GroupName to the constant label key. Instead, this commit changes the way we have defined a label key to include GroupName as part of the label key and use just the label key instead of concatenating GroupName everywhere. This cleans up the code and makes it simple to add tekton internal labels and at the same time retrieve them.

Most of the changes here are done using these two commands:

find . -type f -name "*.go" -print0 | xargs -0 sed -i '' -e 's/pipeline.GroupName+//g'
find . -type f -name "*.go" -print0 | xargs -0 sed -i '' -e 's/pipeline.GroupName +//g'

And I ran a sample pipeline to make sure the labels still have tekton.dev 🤣

kubectl get tr  pipelinerun-print-hello-print-hello-ppbfh -o json | jq .metadata.labels
{
  "app.kubernetes.io/managed-by": "tekton-pipelines",
  "tekton.dev/memberOf": "tasks",
  "tekton.dev/pipeline": "pipeline-print-hello",
  "tekton.dev/pipelineRun": "pipelinerun-print-hello",
  "tekton.dev/pipelineTask": "print-hello",
  "tekton.dev/task": "print-hello"
}

This cleanup was motivated while resuming work on #2891 😜

/kind cleanup

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• Docs included if any changes are user facing
• Tests included if any functionality added or changed
• Follows the commit message standard
• Meets the Tekton contributor standards (including
  functionality, content, code)
• Release notes block below has been filled in or deleted (only if no user facing changes)

Release Notes

The constants defined for the Tekton specific labels now include GroupName(tekton.dev) in the definition, for example:

Before this change:
const TaskLabelKey = "/task"

After this change:
const TaskLabelKey =  GroupName + "/task"

If you are importing these constants in your application from the pipeline source, you don't need to add GroupName anymore. 

[ghost]

I think it might be worth including a release note for this. If anyone's maintaining their own code that imports and uses these constants from the pipelines codebase then they'll need to be aware of the change.

/approve

Looks like the integration failure was just a flake.

/test pull-tekton-pipeline-integration-tests

[vdemeester]

/lgtm

[tekton-robot]

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