MXS-2330 Use simpler queries

Since the current node id can be obtained using the function gtmnid()
the queries for finding out whether a node is in the quorum and whether
it is softfailed can be made simpler.

server/modules/monitor/clustrixmon/clustrix.hh

@@ -24,6 +24,7 @@ enum class Status
 {
     QUORUM,
     STATIC,
+    DYNAMIC,
     UNKNOWN
 };