Fixes: bd19c007 ("Add configuration to retain prometheus data for 1 year")

ansible-lint 6.5.0 complains about:

  name: All names should start with an
        uppercase letter. (name[casing])

These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.

Introduce a new monitoring server with prometheus and alertmanager for
monitoring all our boxes.