fix: boolean flags when enabling collectors

[oneoneonepig]

When enabling boolean flags such as collector.systemd.enable-start-time-metrics, the flag must not specify any value.

Good:

• --collector.systemd.enable-start-time-metrics

Bad:

• --collector.systemd.enable-start-time-metrics=true
• --collector.systemd.enable-start-time-metrics=True
• --collector.systemd.enable-start-time-metrics=

To enable boolean flags, use the following method:

  roles:
    - role: prometheus.prometheus.node_exporter
      vars:
        node_exporter_enabled_collectors:
          - systemd:
              enable-start-time-metrics:

[SuperQ]

Would you please add some molecule tests for this?

[SuperQ]

This still needs a molecule test.

[oneoneonepig]

apologize for the late update, the development has been pending for a while; will include the tests in near future