test: Modify log formatter for verbose logging to help debug issues. (#2327)

* modify log formatter for verbose logging to help debug issues.

* modify log formatter for verbose logging to help debug issues.

Author: meeral-k

google-cloud-bigtable/src/test/resources/logging-verbose.properties

@@ -7,5 +7,5 @@ com.google.cloud.bigtable.data.v2.BigtableDataSettings.level=WARNING
 java.util.logging.ConsoleHandler.level = FINEST
 
 java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
-# time [level] loggerName: message
-java.util.logging.SimpleFormatter.format=%1$tT [%4$-7s] %2$s: %5$s%n
+# [YYYY-MM-DD HH:MM:SS.sss] [level] (loggerName): message
+java.util.logging.SimpleFormatter.format=[%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS.%1$tL.%1$tN] [%4$-7s] (%2$s): %5$s%n