YARN-7430. Enable user re-mapping for Docker containers by default. Contributed by Eric Yang.

(cherry picked from commit 5f0b238a118f3992bd149d8c02e6a1376dee96d7)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -1648,7 +1648,7 @@ public class YarnConfiguration extends Configuration {
       DOCKER_CONTAINER_RUNTIME_PREFIX + "enable-userremapping.allowed";
 
   /** Set enable user remapping as false by default. */
-  public static final boolean DEFAULT_NM_DOCKER_ENABLE_USER_REMAPPING = false;
+  public static final boolean DEFAULT_NM_DOCKER_ENABLE_USER_REMAPPING = true;
 
   /** lower limit for acceptable uids of user remapped user. */
   public static final String NM_DOCKER_USER_REMAPPING_UID_THRESHOLD =