[SPARK-42253][PYTHON] Add test for detecting duplicated error class

### What changes were proposed in this pull request?

This PR proposes to add test for detecting duplicated name of error classes to keep the error class unique.

### Why are the changes needed?

The name of error class should be unique, so we should check if it's duplicated or not.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Manually test in case `COLUMN_IN_LIST` is duplicated as below:
```shell
======================================================================
FAIL [0.006s]: test_error_classes_duplicated (pyspark.errors.tests.test_errors.ErrorsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
...
AssertionError: False is not true : Duplicate error class: COLUMN_IN_LIST

----------------------------------------------------------------------
Ran 2 tests in 0.007s

FAILED (failures=1)
```

Closes apache#39821 from itholic/SPARK-42253.

Lead-authored-by: itholic <haejoon.lee@databricks.com>
Co-authored-by: Hyukjin Kwon <gurwls223@gmail.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
(cherry picked from commit 4d37e78)
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

python/pyspark/errors/error_classes.py

@@ -59,11 +59,6 @@
       "Argument `<arg_name>` must be a DataFrame, got <arg_type>."
     ]
   },
-  "NOT_A_DATAFRAME" : {
-    "message" : [
-      "Argument `<arg_name>` should be a DataFrame, got <arg_type>."
-    ]
-  },
   "NOT_A_DICT" : {
     "message" : [
       "Argument `<arg_name>` should be a dict, got <arg_type>."

python/pyspark/errors/tests/test_errors.py

@@ -16,13 +16,15 @@
 # limitations under the License.
 #
 
+import json
 import unittest
 
+from pyspark.errors.error_classes import ERROR_CLASSES_JSON
 from pyspark.errors.utils import ErrorClassesReader
 
 
 class ErrorsTest(unittest.TestCase):
-    def test_error_classes(self):
+    def test_error_classes_sorted(self):
         # Test error classes is sorted alphabetically
         error_reader = ErrorClassesReader()
         error_class_names = list(error_reader.error_info_map.keys())
@@ -33,6 +35,17 @@ def test_error_classes(self):
                 f"after [{error_class_names[i + 1]}]",
             )
 
+    def test_error_classes_duplicated(self):
+        # Test error classes is not duplicated
+        def detect_duplication(pairs):
+            error_classes_json = {}
+            for name, message in pairs:
+                self.assertTrue(name not in error_classes_json, f"Duplicate error class: {name}")
+                error_classes_json[name] = message
+            return error_classes_json
+
+        json.loads(ERROR_CLASSES_JSON, object_pairs_hook=detect_duplication)
+
 
 if __name__ == "__main__":
     import unittest