Bump protobuf from 5.27.2 to 5.29.5 in /testground/benchmark (#1815)

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 5.27.2 to 5.29.5.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v5.27.2...v5.29.5)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 5.29.5
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]