opentelemetry: Increase limit resources

Only 2 workers for production. It's still maximizing the cpu usage (~99%) and exceeding
the ram usage too [1] (max 14.68Gib).

[1] https://grafana.softwareheritage.org/goto/oPt0RLU4z?orgId=1

Refs. swh/infra/sysadm-environment#4524