DL: Update test sql to reference to tablename created in the same file

Prior to this commit, the tests for restricted access to custom function
table were referencing to a tablename not intended for. The tablename
refereced in the test was actually created in a different test file
which masked the failure. This commit updates the tests to reference to
the actually intended table created in the same file.
diff --git a/src/ports/postgres/modules/deep_learning/test/madlib_keras_custom_function.sql_in b/src/ports/postgres/modules/deep_learning/test/madlib_keras_custom_function.sql_in
index d9a323a..a08f818 100644
--- a/src/ports/postgres/modules/deep_learning/test/madlib_keras_custom_function.sql_in
+++ b/src/ports/postgres/modules/deep_learning/test/madlib_keras_custom_function.sql_in
@@ -160,16 +160,16 @@
 FROM __test_custom_function_table__ WHERE id = 4;
 
 CREATE SCHEMA MADLIB_SCHEMA_aaa;
-CREATE TABLE pg_temp.temp1 AS SELECT * FROM MADLIB_SCHEMA.test_custom_function_table;
-CREATE TABLE pg_temp.MADLIB_SCHEMA AS SELECT * FROM MADLIB_SCHEMA.test_custom_function_table;
-CREATE TABLE MADLIB_SCHEMA_aaa.test_table AS SELECT * FROM MADLIB_SCHEMA.test_custom_function_table;
+CREATE TABLE pg_temp.temp1 AS SELECT * FROM MADLIB_SCHEMA.__test_custom_function_table__;
+CREATE TABLE pg_temp.MADLIB_SCHEMA AS SELECT * FROM MADLIB_SCHEMA.__test_custom_function_table__;
+CREATE TABLE MADLIB_SCHEMA_aaa.test_table AS SELECT * FROM MADLIB_SCHEMA.__test_custom_function_table__;
 
 SELECT assert(MADLIB_SCHEMA.trap_error($$
   SELECT load_custom_function('pg_temp.temp1', custom_function_object(), 'sum_fn', 'returns sum');
 $$) = 1, 'Cannot use non-madlib schemas');
 
 SELECT assert(MADLIB_SCHEMA.trap_error($$
-  SELECT load_custom_function('test_custom_function_table UNION pg_temp.temp1',
+  SELECT load_custom_function('__test_custom_function_table__ UNION pg_temp.temp1',
     custom_function_object(), 'sum_fn', 'returns sum');
 $$) = 1, 'UNION should not pass');