Allow proper setCount SLAs across zones (#8752)

Fixes scenario where zones are appropriately
handled, along with supporting overriding set
count. The new fix also ensures that we handle
the various setup types properly.

Update documentation to properly indicate the
behavior.

Fixes #8750

Co-authored-by: Nitish Tiwari <nitish@minio.io>

cmd/test-utils_test.go

@@ -1894,7 +1894,8 @@ func ExecObjectLayerAPITest(t *testing.T, objAPITest objAPITestType, endpoints [
 		t.Fatalf("Unable to initialize server config. %s", err)
 	}
 
-	globalIAMSys = NewIAMSys()
+	newAllSubsystems()
+
 	globalIAMSys.Init(objLayer)
 
 	buckets, err := objLayer.ListBuckets(context.Background())
@@ -1902,7 +1903,6 @@ func ExecObjectLayerAPITest(t *testing.T, objAPITest objAPITestType, endpoints [
 		t.Fatalf("Unable to list buckets on backend %s", err)
 	}
 
-	globalPolicySys = NewPolicySys()
 	globalPolicySys.Init(buckets, objLayer)
 
 	credentials := globalActiveCred