Follow-up from "Refactor pipeline header actions into new component"

Maintenance issue to add more test coverage to spec/frontend/ci/pipeline_details/header/pipeline_details_header_spec.js for certain use-cases.

The following discussion from !148100 (merged) should be addressed:

• @lorenzvanherwaarden started a discussion:

  suggestion (non-blocking): I see there is test coverage for isRetrying, but not for isCancelling and isDeleting props sent to the HeaderActions. Should we add those? I'm fine with a follow-up for it as this MR is simply about moving to a separate component and the coverage wasn't present before.