[QA] Fix arguments passed to RSpec::Core::Runner

What does this MR do?

Currently, if you try to pass --tag foo to an instance-level QA scenario, the orchestrated tag is still excluded, which isn't what we want. Here is an example: https://gitlab.com/gitlab-org/gitlab-qa/-/jobs/95489725.

This MR fixes this use-case and adds several test cases.

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides