* if variable to bind an exporter container to a host port is set, have matrix-domain.conf (nginx) support this

* manipulate some variables to account for just port numbers or 0.0.0.0 IPs

* Make sure to use the right variable in the init.yml files

* Update roles/matrix-prometheus-node-exporter/tasks/init.yml

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* Update roles/matrix-prometheus-postgres-exporter/tasks/init.yml

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* remove extraneous variables and whitespace

Co-authored-by: Luca Bilke <luca@gmail.com>
Co-authored-by: Slavi Pantaleev <slavi@devture.com>