Mark skipped PipelineRuns as successful on GitHub

[zregvart]

If a Check suite is marked as required on GitHub it must report successful result. Currently there is no option to mark the Check suite as skipped (see https://github.com/orgs/community/discussions/13690). Perhaps a configurable option could be added to PaC to mark the Check suite as successful even though the PipelineRun was skipped.
What we're trying to do is not to run pipelines for changes that are unrelated to the pipeline in question, using pipelinesascode.tekton.dev/on-cel-expression annotation and we would not like to make the check suite not required as then the changes could get merged even though the pipeline failed.