reqwest-client -> reqwest-blocking-client

[jerbaroo]

Tested by copilot:

Diagnosis confirmed by reproduction. I built with reqwest-client (current master) and ran the server with OTEL_EXPORTER_OTLP_ENDPOINT
set:

 thread 'OpenTelemetry.Traces.BatchProcessor' (152196) panicked at .../core/src/ops/function.rs:250:5:
 there is no reactor running, must be called from the context of a Tokio 1.x runtime

Note the thread name: OpenTelemetry.Traces.BatchProcessor — the dedicated std::thread with no Tokio runtime, exactly as predicted.

Your change fixes it. Same binary, same env, with reqwest-blocking-client: runs to the timeout with zero panics. Verified via cargo tree
that opentelemetry-otlp now resolves reqwest-blocking-client and no longer reqwest-client

[ReinierMaas]

LGTM! Thanks for finding and fixing.

[jerbaroo]

@OpsBotPrime merge and tag

[OpsBotPrime]

Rebased as 41c30ff, waiting for CI …

[OpsBotPrime]

CI job 🟡 started.

[OpsBotPrime]

@jerbaroo I tagged your PR with v62. Please wait for the build of 41c30ff to pass and don't forget to deploy it!