otel-metrics: enable remote write from prom to fb

Some users reported that the current implementation of the metrics flow
it is causing errors in the fluent bit components that scrape the metrics
from the local prometheus and forwards to open telemetry.

This commits inverts the paradigm and now it is prometheus the one doing
the remote write into the local fluent bit. After that, fluent bit is
doing a remote write as it was doing previously into the monitoring infra.

Reported-at: https://its.cern.ch/jira/browse/MONIT-4077


Signed-off-by: Guillermo Facundo Colunga <guillermo.facundo.colunga@gmail.com>
Signed-off-by: Guillermo Facundo Colunga <guillermo.facundo.colunga@cern.ch>