test(sqlserver): rename ALTER TABLE IF EXISTS test to avoid name collision

Author: vistart

…re/backend/test_alter_table_if_exists.py …nd/test_alter_table_if_exists_backend.pytests/rhosocial/activerecord_sqlserver_test/feature/backend/test_alter_table_if_exists.py renamed to tests/rhosocial/activerecord_sqlserver_test/feature/backend/test_alter_table_if_exists_backend.py tests/rhosocial/activerecord_sqlserver_test/feature/backend/test_alter_table_if_exists.py renamed to tests/rhosocial/activerecord_sqlserver_test/feature/backend/test_alter_table_if_exists_backend.py

@@ -1,4 +1,4 @@
-# tests/rhosocial/activerecord_sqlserver_test/feature/backend/test_alter_table_if_exists.py
+# tests/rhosocial/activerecord_sqlserver_test/feature/backend/test_alter_table_if_exists_backend.py
 """Tests for SQL Server ALTER TABLE IF [NOT] EXISTS handling.
 
 SQL Server supports ``DROP COLUMN IF EXISTS`` and ``DROP CONSTRAINT