No forward for the OTEL gRPC stuff

[fulmicoton]

No sure if it is a problem or not but the following does not work.

Node 1 port 7280

QW_ENABLE_OPENTELEMETRY_OTLP_EXPORTER=true \
OTEL_EXPORTER_OTLP_ENDPOINT=http://127.0.0.1:7281 \
./quickwit run --service searcher --service metastore --service control_plane --service janitor

Node 2 port 8280

./quickwit run --service indexer

Node 1 is sending its own tracing data to itself, and forward does not happen (contrary to what happens for the ingest api).

[fmassot]

This can be fixed very simply by running the OTLP gRCP services.