Per https://github.com/openshift/cluster-ingress-operator/pull/1192#discussion_r1988098018, once we bump to OSSM 3, we need check whether OSSM 3 has a mutating webhook (or other implementation detail) that requires running the Gateway API tests in serial.

The issue referenced in that GitHub comment is that OSSM 2 has a "sidecar-injector.istio.io" mutating webhook for servicemeshcontrolplanes. When this webhook is installed, then until the webhook and Istiod are both ready, pod creation fails for any and all pods on the cluster, which can cause unrelated tests to fail if they run in parallel with the Gateway API tests that install OSSM 2.

This spike has two possible outcomes:

• We determine that it is safe to run the Gateway API tests that install OSSM 3 in parallel with unrelated tests. In this case, we can update the Gateway API tests to run in parallel once more.
• We determine that it is unsafe to run the Gateway API tests that install OSSM 3 in parallel. In this case, we need to discuss the issue with the Service Mesh team, try to find a solution, and at a minimum document for the time being that OSSM's installation can cause temporary disruption to cluster workload by blocking pod creation.