HBASE-26662 User.createUserForTesting should not reset UserProvider.g…

…roups every time if hbase.group.service.for.test.only is true (#4029)

Signed-off-by: Josh Elser <elserj@apache.org>
Signrd-off-by: Duo Zhang <zhangduo@apache.org>

hbase-common/src/main/java/org/apache/hadoop/hbase/security/User.java

@@ -351,8 +351,7 @@ public <T> T runAs(PrivilegedExceptionAction<T> action)
     public static User createUserForTesting(Configuration conf,
         String name, String[] groups) {
       synchronized (UserProvider.class) {
-        if (!(UserProvider.groups instanceof TestingGroups) ||
-            conf.getBoolean(TestingGroups.TEST_CONF, false)) {
+        if (!(UserProvider.groups instanceof TestingGroups)) {
           UserProvider.groups = new TestingGroups(UserProvider.groups);
         }
       }