jenkins-rel: unify branch cut jobs

Using plugin https://plugins.jenkins.io/parameterized-scheduler/ we can pass different parameters to handle both the pretest and weekly train branch cut cases in a single job.

The security patches pretest job is modified so it can also handle the weekly branch cut case. Up until now, the weekly cut relied implicitly on the nightlies to verify the security patches. The change decouples the two cases, and makes sure we test the patches on the actual train branch created on Tuesdays

Bug: T350065