Schema metadata checks ignore schemas owned by rdsadmin

[rwc9u]

We were setting up the collecting of schema metrics to database monitoring for one of our databases. The metrics for tables in our public schema were not being reported. We identified that the table is owned by rdsadmin and schemas owned by rdsadmin are ignored

https://github.com/DataDog/integrations-core/blob/master/postgres/datadog_checks/postgres/metadata.py#L105-L115

I'm not sure why the schema is owned by rdsadmin. I suspect it was an artifact of our migration from a heroku to AWS aurora migration 4 years ago.

Looking at the SCHEMA_QUERY above the other ignores seem to get rid of other schemas that we wouldn't be interested in (e.g. pg_ schemas). Could we relax this query to remove the

AND r.rolname  !=       'rdsadmin'