[6.15.z] [comp-eval] UI>content>errata tab, Pagination testing

[Satellite-QE]

Cherrypick of PR: #13767

Update Errata UI Pagination testing

• to standards for 6.15.0 for setup w/ global registration, and new host UI views
• depends on airgun#1152

Implement

• use of registered host fixture, setup w/ global registration, subscribed to content.
• method to publish and promote cv, wait for any task(s).
• migrate Airgun UI view; from legacy contenthost UI > errata page ,
  to new host UI > content > errata tab .

Handle Failure: expected updated pagination, but remains the same:

• Sometimes, applicable_errata_count for the host has already updated after some install, but pagination on the table remains the same as before. I used wait_for to give the new host>content>errata tab time to reload with updated entries /total_items/total_pages etc. Timeout set for 30s on the tab loading new table and pagination, in case satellite is slow.

Affected tests and PRT case:

• test_content_host_errata_page_pagination renamed to test_host_content_errata_tab_pagination
• test_end_to_end by modifying fixture registered_contenthost

trigger: test-robottelo
pytest: tests/foreman/ui/test_errata.py -k 'test_host_content_errata_tab_pagination or test_end_to_end'
airgun: 1152

[Satellite-QE]

trigger: test-robottelo
pytest: tests/foreman/ui/test_errata.py -k 'test_host_content_errata_tab_pagination or test_end_to_end'
airgun: 1152