rebase: bump google.golang.org/grpc from 1.72.2 to 1.73.0

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.72.2 to 1.73.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.72.2...v1.73.0)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-version: 1.73.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/go.opentelemetry.io/otel/CONTRIBUTING.md

@@ -181,6 +181,18 @@ patterns in the spec.
 For a deeper discussion, see
 [this](https://github.com/open-telemetry/opentelemetry-specification/issues/165).
 
+## Tests
+
+Each functionality should be covered by tests.
+
+Performance-critical functionality should also be covered by benchmarks.
+
+- Pull requests adding a performance-critical functionality
+should have `go test -bench` output in their description.
+- Pull requests changing a performance-critical functionality
+should have [`benchstat`](https://pkg.go.dev/golang.org/x/perf/cmd/benchstat)
+output in their description.
+
 ## Documentation
 
 Each (non-internal, non-test) package must be documented using