Investigate request context activation/deactivation in grpc interceptor

[manovotn]

This is a follow up to #37741 where we didn't resolve the behavior in grpc.

The examples in the above issue are still valid (except the first one which was already addressed) and @michalvavrik has a branch with them over at https://github.com/michalvavrik/quarkus/tree/feature/grpc-event-observer-repro.

We should look into what's happening with req. context activation/deactivation and context state in these scenarios.
The issue seems to be with VertxCurrentContext#remove never really removing req. context which, in cases of manual context deactivation, leads to req. context permanently appearing to be active.

[quarkus-bot]

/cc @alesj (grpc), @cescoffier (grpc)