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

This reverts commit edf6f68.

See HBASE-22874

Author: apurtell

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

@@ -119,7 +119,7 @@
  * </li>
  * </ol>
  */
-@InterfaceAudience.Public
+@InterfaceAudience.Private
 public final class Canary implements Tool {
   /**
    * Sink interface used by the canary to output information