[CORDA-1763]: Add node CLI option for validating configuration. (#4121)

testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/DriverDSLImpl.kt

@@ -777,6 +777,7 @@ class DriverDSLImpl(
                     "visualvm.display.name" to "corda-${config.corda.myLegalName}"
             )
             debugPort?.let {
+                systemProperties += "log4j2.level" to "debug"
                 systemProperties += "log4j2.debug" to "true"
             }