[Monitoring Role]: Use ansible_host values when present for configuring Scylla and Manager targets

[vladzcloudius]

HEAD: 7b7e913

Description

Monitoring Role always uses a Manager host from the inventory.
However, this name may not be resolvable in which case ansible_host will be provided.

The same applies to Scylla hosts.

We should always use ansible_host if it's defined in the inventory.