Set grafana-server user and password in ceph-dashboard role
Set grafana-server user and password in ceph-dashboard role

This change adds two tasks to set grafana-api user and password
that are required to inject dashboard layouts to the external
grafana instance.
Without these two parameters the ceph-ansible playbook fails
showing an authorization error (HTTPError: 401 Client Error:
Unauthorized").

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1767365
Signed-off-by: fmount <e4471f5362e63527847b85ad100e4685bab084fa@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible