Summary:
PG upstream commit e9d4001ec592bcc9a3332547cb1b0211e8794f38 introduced `create_role` regress test. This revision ports this test to YB.

Jira: DB-15530

Test Plan: ./yb_build.sh --java-test 'TestPgRegressPgAuth#schedule'

Reviewers: skumar, stiwary, devansh.saxena, jason

Reviewed By: devansh.saxena, jason

Subscribers: jason, yql

Differential Revision: https://phorge.dev.yugabyte.com/D42157