pgAdmin4: Cleanup in role dependency test cases

Hi Dave,

Role dependency test cases are failing due to database error *'ERROR: cache
lookup failed for database XXXXXX'. *Test-suite throwing error on* "DROP
ROLE <role_name>".*
This is intermittent issue I was executing test cases on all
servers (pg9.2-10 and ppas9.2-10)

Somehow the 'DROP database' didn't drop the shared dependencies correctly
in role dependency test cases.
PostgreSQL still thinks that Role owns 1 table in the database which is
dropped now .Due to that role was not able to drop.
This could be a bug in PG. Anyway, since the database is dropped, it is
safe to manually remove the user as it is not of any use more.

Please find the patch.

Thanks.

--
Regards,
Navnath Gadakh

EnterpriseDB Corporation
The Enterprise PostgreSQL Company