QE: Fix GH validation core stage

[srbarrios]

What does this PR change?

Having refactored in a previous PR how we handle synchronization of channels, we missed the fact that we don't need a different Cucumber feature on the GH Validation in order to create the fake repositories, therefore we can delete it and re-use the same Cucumber feature that we use in our CI test suite.

GUI diff

No difference.

• DONE

Documentation

• No documentation needed

• DONE

Test coverage

• Cucumber tests were adapted

• DONE

Links

No Ports:

• Manager-4.3 (For now, we did not port GH Validations to Spacewalk)

• DONE

Changelogs

Make sure the changelogs entries you are adding are compliant with https://github.com/uyuni-project/uyuni/wiki/Contributing#changelogs and https://github.com/uyuni-project/uyuni/wiki/Contributing#uyuni-projectuyuni-repository

If you don't need a changelog check, please mark this checkbox:

• No changelog needed

If you uncheck the checkbox after the PR is created, you will need to re-run changelog_test (see below)

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_pgsql_tests"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[github-actions]

👋 Hello! Thanks for contributing to our project.
Acceptance tests will take same time (aprox. 1h), please be patient ☕
You can see the progress at the end of this page and at https://github.com/uyuni-project/uyuni/pull/7739/checks
Once tests finish, if they fail, you can check 👀 the cucumber report. See the link at the output of the action.
You can also check the artifacts section, which contains the logs at https://github.com/uyuni-project/uyuni/pull/7739/checks.
See the troubleshooting guide if you need any help.

⚠️ You should not merge if acceptance tests fail to pass. ⚠️

Happy hacking!