RTC plugin flooding the log

Every time the plugin pinged the RTC server, it logged a message stating
the connection was OK. The log level was INFO, so the logs were flooded
with this message (a new line every 13-15 seconds).

Lower the log level to DEBUG.

Change-Id: Ic3548bbbadbc22011682203ebc807beec0b57b8d
diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/rtc/RTCItsFacade.java b/src/main/java/com/googlesource/gerrit/plugins/its/rtc/RTCItsFacade.java
index e8526a1..24b8d69 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/rtc/RTCItsFacade.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/rtc/RTCItsFacade.java
@@ -55,7 +55,7 @@
       this.injector = injector;
       this.gerritConfig = gerritConfig;
       client().ping();
-      log.info("Connected to RTC at " + getRtcUrl() + " as admin user "
+      log.debug("Connected to RTC at " + getRtcUrl() + " as admin user "
           + getRtcUser());
     } catch (Exception ex) {
       log.warn("RTC is currently not available", ex);