Extend airgap to use gitaly cluster for a broader range of tests

What does this MR do and why?

Part of https://gitlab.com/gitlab-org/gitlab-qa/-/issues/694+
Follow up to https://gitlab.com/gitlab-org/gitlab-qa/-/merge_requests/1098+

Modifying the Airgapped scenario to use a GitalyCluster setup against a broader set of tests.

The planned changes here will

• Extends the suite of tests that the Airgapped test runs against to the majority of the E2E test suite

  • exception made for tests marked as :gitlab, and :skip_live_environent for this iteration
    • these tags help exclude a number of tests which reach out to external sites such as gitlab.com and integrations with jenkins

• reintroduces the use of iptables on the Gitlab instance to restrict network accesss

  • this was removed in https://gitlab.com/gitlab-org/gitlab-qa/-/commit/f5c996e1ad15eb3cce69c1aad3c132360ace48d2 but that decision was premature as with the wider set of tests, for now at least we need to have the ability to access registry.gitlab.com to download runner images for tests that make use of runners

How to set up and validate locally

Make use of bundle exec exe/gitlab-qa Test::Instance::Airgapped for various specs or suites e.g.

bundle exec exe/gitlab-qa Test::Instance::Airgapped EE qa/specs/features/browser_ui/3_create/repository/protected_tags_spec.rb --no-teardown

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.