As a job author, I would like the pipeline timeout GRACE_PERIOD exposed as a configurable option so that I can allow for teardown steps that take longer than 5s or 60s.

I use the timeout option on a stage, but during the normal course of operations if that timeout engages items in an always post step only get that grace period to complete.  For processes with extensive cleanup, you see `Body did not finish within grace period; terminating with extreme prejudice` and it force-kills what's running.  This can leave some cleanup process incomplete.  I'd like to see an option in the timeout step to specify how long that grace period ought to be.

 Relevant code link: https://github.com/jenkinsci/workflow-basic-steps-plugin/blob/3ecc7bbd91182e330a23a9e661ae1cdfa2d2b55e/src/main/java/org/jenkinsci/plugins/workflow/steps/TimeoutStepExecution.java#L41