[6.15.z] Errata coverage for CV Incremental Update

[Satellite-QE]

Cherrypick of PR: #13994

Purpose

• Add coverage for incremental update, that it is available when expected, and
• that the expected host's content-view and environment(s) are are updated as expected, and
• the available errata/packages to host are updated by the incremental version as expected.
• we can install updated packages and see the expected (filtered-security only) applicable errata/count drops, and
  the applicable packages count drops.
• modification to helper method cv_publish_promote, which did not always filter environment ids for promotion as expected.

Coverage reason

We already have some testing for if any incremental update is needed on a single view/environment, test_positive_incremental_update_required:

• But the existing test doesn't check the successful update and new CV version itself (contained errata/content). Or how the registered host's applicability is affected by the new version.

PRT Case

trigger: test-robottelo
pytest: tests/foreman/api/test_errata.py::test_positive_incremental_update_apply_to_envs_cvs

[Satellite-QE]

trigger: test-robottelo
pytest: tests/foreman/api/test_errata.py::test_positive_incremental_update_apply_to_envs_cvs

[Satellite-QE]

PRT Result

Build Number: 5704
Build Status: SUCCESS
PRT Comment: pytest tests/foreman/api/test_errata.py::test_positive_incremental_update_apply_to_envs_cvs
Test Result : ================= 1 passed, 11 warnings in 1033.40s (0:17:13) ==================