rebase: bump google.golang.org/grpc from 1.69.4 to 1.70.0

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.69.4 to 1.70.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.69.4...v1.70.0)

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

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

vendor/go.opentelemetry.io/otel/sdk/trace/span.go

@@ -639,10 +639,7 @@ func (s *recordingSpan) dedupeAttrsFromRecord(record map[attribute.Key]int) {
 			record[a.Key] = len(unique) - 1
 		}
 	}
-	// s.attributes have element types of attribute.KeyValue. These types are
-	// not pointers and they themselves do not contain pointer fields,
-	// therefore the duplicate values do not need to be zeroed for them to be
-	// garbage collected.
+	clear(s.attributes[len(unique):]) // Erase unneeded elements to let GC collect objects.
 	s.attributes = unique
 }