Port jobNamespace fix to 0-81-stable

What does this MR do?

Port the fix from !522 (merged) to 0-81-stable.

Why was this MR needed?

The jobNamespace feature is broken: role and rolebinding are getting deployed to the wrong namespace. A fix exists in !522 (merged) - this is a port of this fix.

What's the best way to test this MR?

Tests have been added by @Jellyfrog

What are the relevant issue numbers?

Part of fixing the regression in #413 (closed)

Comments for the GitLab Duo Review

@GitLabDuo The service account that is target of the session server rolebinding resides in the runner managers namespace, as well as the runner manager and the service object for the session server. It´s the runner manager that wants to look up the session server service object in it´s own namespace and therefore needs this role and role-binding in the same namespace.