[notifiers/github] Status Display Names

[wlynch]

Expected Behavior

Re-runs of TaskRuns should overwrite previous statuses.

Actual Behavior

Since we derive the status name from the Run name, unique runs will create different statuses, leaving the old statuses unmodified.

Additional Info

This would likely benefit from tektoncd/pipeline#3466, but in the meantime we can likely just use an annotation to modify this behavior for just this project.

/assign @wlynch

[wlynch]

Fixed in #779