roachtest: use internal name when setting PanicOnAssertions

The user visible name for setting PanicOnAssertions was not
added until 23.2. Attempting to use this on mixed version tests
that upgrade from an earlier version will throw an unknown
cluster setting error

Author: DarrylWong

pkg/roachprod/install/cockroach.go

@@ -1394,7 +1394,9 @@ func (c *SyncedCluster) generateClusterSettingCmd(
 		"enterprise.license":   license,
 		// N.B. We now enable `PanicOnAssertions` for all roachprod clusters.
 		// (See https://github.com/cockroachdb/cockroach/issues/136858)
-		"debug.panic_on_failed_assertions.enabled": "true",
+		// Use the internal name instead of the user visible name, which wasn't
+		// added until 23.2, to avoid breaking mixed version tests.
+		"debug.panic_on_failed_assertions": "true",
 	}
 	for name, value := range c.ClusterSettings.ClusterSettings {
 		clusterSettings[name] = value