[6.15.z] Capsule N-Minus testing

[Satellite-QE]

Cherrypick of PR: #12939

Changes include:

• A new pytest plugin for Capsule N-minus testing that would smart collect all capsule specific tests excluding few.
  • New option of --n-minus for collecting only capsule specific tests
  • tests using the caspule_factory are collected
  • destructive, maintain and puppet tests are excluded since they need a separate satellite
• Introduces new setting hostname in capsule conf to take capsule hostname given from CI.
• _target_capsule_host context manager now returns the cached capsule taken from CI instead of spinning of new capsule for everytime.
• The CI capsule is registered once/cached to CDN for RHEL contents needed by some tests at the start of the n-minus testing and would be unregistered at the end of test session.
• Since we are using single capsule already integrated with satellite in CI, we are escaping the capsule setup from fixtures for n-minus testing
• Some test amendments for nminus testing.

[Satellite-QE]

trigger: test-robottelo
pytest: --uses-fixtures capsule_factory tests/foreman/api
provisioning: true
env:
    ROBOTTELO_server__deploy_arguments__deploy_sat_version: '6.15.0'
    ROBOTTELO_server__deploy_arguments__deploy_snap_version: ''
    ROBOTTELO_server__version__release: '6.15.0'
    ROBOTTELO_server__version__snap: ''

[Satellite-QE]

PRT Result

Build Number: 6016
Build Status: UNSTABLE
PRT Comment: pytest --uses-fixtures capsule_factory tests/foreman/api --external-logging --include-onprem-provisioning
Test Result : = 3 failed, 27 passed, 7 skipped, 2765 deselected, 2621 warnings, 2 errors in 13337.90s (3:42:17) =

[jyejare]

The test failures here are not related to the framework changes and same as master PR. Hence we should be good to merge it !

Merging it as we Caspule NMinus pipelines merged and will be triggered sooner !!