Gracefully handle existing default login roles If multiple databases are created in the same PostgreSQL cluster, existing roles are now properly re-used. This also fixes running database tests on a cluster that already has these roles, which was broken since rev. 5e38667f740c, because it silently fixed a test for existance of roles that failed if proper creation of the role 'sysadmin' failed during setup of the test database.

# documentation
**/README*
**/docs
**/*.md

# backend binary
cmd/gemma/gemma

# Dependency directories
.buildbase
**/node_modules

# local dotenv environment variables file
client/.env.local

# Tags tables
**/TAGS