Fix build error when revision is shorter than 8 chars

It will through ArrayOutOfBoundException if we build alluxio in a node
which have no git installed, and the `VERSION` would be shorter than 8,
even empty string, so substring(8) cannot work anymore.

This PR check there are more than 8 chars in the `VERSION` first,
otherwise, do not cut the `VERSION` string.

pr-link: #16888
change-id: cid-4e02cc9214317d86bba9d00a6121c5f013dd3255

core/common/src/main/java/alluxio/RuntimeConstants.java

@@ -36,7 +36,8 @@ public final class RuntimeConstants {
     }
   }
 
-  public static final String REVISION_SHORT = ProjectConstants.REVISION.substring(0, 8);
+  public static final String REVISION_SHORT = ProjectConstants.REVISION.length() > 8
+      ? ProjectConstants.REVISION.substring(0, 8) : ProjectConstants.REVISION;
   public static final String VERSION_AND_REVISION_SHORT =
       VERSION + "-" + REVISION_SHORT;