downgrade prometheus exporter dependency

[codeboten]

Downgrades the prometheus exporter dependency. This is to address the following issue documented in the release notes

❗ Known Issues ❗

• Due to a bug in the prometheus exporter, if you are configuring a prometheus exporter, the collector's internal metrics will be emitted with an unexpected suffix in its name. For example, the metric otelcol_exporter_sent_spans__spans__total instead of otelcol_exporter_sent_spans_total. The workaround is to manually configure without_units: true in your prometheus exporter config

  service:
    telemetry:
      metrics:
        readers:
          - pull:
              exporter:
                prometheus:
                  host: 0.0.0.0
                  port: 8888
                  without_units: true

  If you are using the collector's default Prometheus exporter for exporting internal metrics you are unaffected.

[codeboten]

closing in favour of #13429