grpc: propagate tracing headers when using google grpc streams

[cainelli]

Commit Message: grpc: propagate tracing headers when using google grpc streams Additional Description: Following up on https://github.com/envoyproxy/envoy/pull/33665, which adds tracing to Envoy gRPC streams, this PR introduces the same support using Google gRPC for completeness to https://github.com/envoyproxy/envoy/issues/21119.

Risk Level: Low Testing: The same manual tests described in https://github.com/envoyproxy/envoy/pull/33665, besides the integration tests of extproc are also testing google grpc now. Docs Changes: N/A Release Notes: N/A

[repokitteh-read-only[bot]]

As a reminder, PRs marked as draft will not be automatically assigned reviewers, or be handled by maintainer-oncall triage.

Please mark your PR as ready when you want it to be reviewed!

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/34395 was opened by cainelli.

see: more, trace.

[cainelli]

/retest

[adisuissa]

/wait-any

[tyxia]

/wait-any

@cainelli Please also look at the CI failure. Looks like they are legit.