Periodically run E2E tests against the merged (must have passed E2E
gating) code to detect breakages due to external changes or flaky
failures.
Also supports debugging Helm-related failures in other repositories, by
verifying (or not) what's passing here.
Use the same test matrix as the current E2E job.
Mirrors similar tests in other Submariner repositories.
Signed-off-by: Daniel Farrell <dfarrell@redhat.com>