Summary:
The `PgFKeyTest.DeferredFKTableLocality` is required to run ddl in separate transaction. For this purpose the `FLAGS_ysql_yb_ddl_transaction_block_enabled` flag is explicitly set to false.
Jira: DB-18989

Test Plan: Jenkins

Reviewers: stiwary, bkolagani, myang, pjain, patnaik.balivada

Reviewed By: myang

Subscribers: yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D48121