Fix Grafana metrics

[pefontana]

• Fix OTLP (OpenTelemetry Protocol) typo
• Fix Grafana Clients dashboard to display client selector properly when running locally

To run it:

Local Testing with Telemetry

1. Start the telemetry stack:
   docker compose -f telemetry/docker-compose.yml up -d

2. Start localnet with a test run:
   just dev setup-solana-localnet-light-test-run

3. In a new terminal, start a training client with telemetry:
   OTLP_METRICS_URL="http://localhost:4318/v1/metrics"
   OTLP_LOGS_URL="http://localhost:4318/v1/logs"
   just dev start-training-localnet-light-client

4. Verify in Grafana:

• Open http://localhost:3000 and go to Clients dashboard