Revert "HBASE-22823 Mark Canary as Public/Evolving"

This reverts commit 1f7458d.

See HBASE-22874

Author: apurtell

hbase-server/src/main/java/org/apache/hadoop/hbase/tool/Canary.java

@@ -108,7 +108,7 @@
  * 3. zookeeper mode - for each zookeeper instance, selects a zNode and
  * outputs some information about failure or latency.
  */
-@InterfaceAudience.Public
+@InterfaceAudience.Private
 public final class Canary implements Tool {
   // Sink interface used by the canary to outputs information
   public interface Sink {