[telemetry][TC] Stepping down from Telemetry PTL

Hi there, due to other time commitments, I would need to step down from Telemetry PTL and proposed Juan Larriba -- the previous PTL -- to take over[1]. I won't be far, but I also believe the project is in better hands of a person who is nearer to the code these days. Matthias [1] https://review.opendev.org/c/openstack/governance/+/964516