Fix telemetry-induced-telemetry in OTLP Exporter

[cijothomas]

https://github.com/open-telemetry/opentelemetry-rust/pull/2868/files fixes the issue of Otel's own operations generating telemetry and feeding that to OTel itself. However, this works only if Otel's Context is properly propagated.

This is not done by libraries like hyper, tonic etc. when they cross thread-boundaries. This issue is opened to address this.

[cijothomas]

https://github.com/open-telemetry/opentelemetry-rust/issues/761 linking to old issue for the same problem.

[cijothomas]

https://github.com/krojew/tracing-elastic-apm/blob/master/src/apm_client.rs#L103-L104 -- most promising solution we can explore for OTLP

[cijothomas]

Self-assigned. Will investigate the feasibility and update the status.