priority class: Add an exception for OSSM

This commit is related to OCPBUGS-54568.

https://issues.redhat.com/browse/OCPBUGS-54568

* test/extended/pods/priorityclasses.go (excludedPriorityClassPods): Add an
override for the OSSM operator.

Author: Miciah

Diff for: test/extended/pods/priorityclasses.go

@@ -30,6 +30,12 @@ var excludedPriorityClassPods = map[string][]string{
 		"configure-alertmanager-operator",
 		"osd-cluster-ready",
 	},
+
+	// OLM does not provide an option to set priority class on pods created
+	// by subscription.
+	"openshift-operators": {
+		"servicemesh-operator3-",
+	},
 }
 
 var _ = Describe("[sig-arch] Managed cluster should", func() {