CASS-1870 Quieter logs when we try to create a JMX connection before …

…C* has started. (#910)

* CASS-1870 remove dead code, clean imports

* CASS-1870 Remove noisy log statements from CassandraAdmin. All removed logs are redundant with what
JMXNodeTool produces and sometimes print entire stack traces when the Exception is not a surprise
(i.e., C* is not up yet)

* CASS-1870 Quieter logs any time CassandraTunerService.updateServicePost is run before C* starts.

priam/src/main/java/com/netflix/priam/tuner/CassandraTunerService.java

@@ -38,9 +38,10 @@ public void updateServicePost() throws Exception {
         // Update the cassandra to enable/disable new incremental files.
         new RetryableCallable<Void>(6, 10000) {
             public Void retriableCall() throws Exception {
-                JMXNodeTool nodetool = JMXNodeTool.instance(configuration);
-                nodetool.setIncrementalBackupsEnabled(
-                        IncrementalBackup.isEnabled(configuration, backupRestoreConfig));
+                try (JMXNodeTool nodeTool = JMXNodeTool.instance(configuration)) {
+                    nodeTool.setIncrementalBackupsEnabled(
+                            IncrementalBackup.isEnabled(configuration, backupRestoreConfig));
+                }
                 return null;
             }
         }.call();