[override_config_table] ignore non user config table in empty input compare (#7159)

Summary: Bypass non user config table in empty intput test.

What is the motivation for this PR?
The empty input compare failed in FLEX_COUNTER_TABLE comparison. This specific table will have derivative change after load_minigraph. We can skip it as it is not user config.

How did you do it?
Bypass non user config table in empty input compare.

How did you verify/test it?
Local test.

Author: wen587

tests/override_config_table/test_override_config_table.py

@@ -103,8 +103,13 @@ def load_minigraph_with_golden_empty_input(duthost):
     reload_minigraph_with_golden_config(duthost, empty_input)
 
     current_config = get_running_config(duthost)
-    pytest_assert(initial_config == current_config,
-                  "Running config differs.")
+    for table in initial_config:
+        if table in NON_USER_CONFIG_TABLES:
+            continue
+        pytest_assert(
+            initial_config[table] == current_config[table],
+            "empty input compare fail! {}".format(table)
+        )
 
 
 def load_minigraph_with_golden_partial_config(duthost):