Foreman-maintain testing with upstream nightly

[ntkathole]

Goal: To perform foreman-maintain testing with upstream nightly.

Description: Currently our automation run in Jenkins get triggered automatically according to satellite builds. Extend the support for upstream nightly as well so that we can catch the issues in early phase.
This will include setting up upstream nightly instance and running tests from testfm on top of it.

Limitations:

• Currently upstream nightly upgrade support is still in development
  Fixes #19942 - upstream upgrade - 1.14 -> 1.15 -> 1.16 theforeman/foreman_maintain#230

Till we have upgrade support in foreman-maintain, we can run tests related to backup, restore and services functionality on upstream.

Action Item:
See how can we utilize existing upstream nightly provisioning instance and trigger testfm automation.