Add NADE ownership to tests_common/deflake.py (#1691)

This file is part of a NADE initiative to reduce test flakiness, we should be codeowners on it.

.github/CODEOWNERS

@@ -6,6 +6,7 @@
 src/snowflake/cli/api/utils/ @snowflakedb/snowcli @snowflakedb/nade
 **/test_data @snowflakedb/snowcli @snowflakedb/nade
 tests_e2e/conftest.py @snowflakedb/snowcli @snowflakedb/nade
+tests_common/deflake.py @snowflakedb/snowcli @snowflakedb/nade
 
 ## Workspaces (shared ownership)
 src/snowflake/cli/_plugins/workspace/ @snowflakedb/snowcli @snowflakedb/nade