Don't warn when we match an issue

Since the desired behavior is to match, we don't want to spam
the logs with warnings. Continue to show when debugging.

Change-Id: Ib3f544fc44ec8344d14dd339cbc3aa928d69ff18
diff --git a/hooks-its/src/main/java/com/googlesource/gerrit/plugins/hooks/validation/ItsValidateComment.java b/hooks-its/src/main/java/com/googlesource/gerrit/plugins/hooks/validation/ItsValidateComment.java
index f157730..61dcc4d 100644
--- a/hooks-its/src/main/java/com/googlesource/gerrit/plugins/hooks/validation/ItsValidateComment.java
+++ b/hooks-its/src/main/java/com/googlesource/gerrit/plugins/hooks/validation/ItsValidateComment.java
@@ -122,7 +122,7 @@
               + comment + " but not found on ITS");
         } else {
           exist = true;
-          log.warn("Workitem " + issueId + " found");
+          log.debug("Workitem " + issueId + " found");
         }
       } catch (IOException ex) {
         log.warn("Unexpected error accessint ITS", ex);