feat: Bump protobuf to v26.1 and bazel to 7.5.0

MR bumps used protobuf version to v26.1. Moreover it is necessary to bump bazel to a more recent version, i.e. 7.5.0.

Cleanup of obsolete stuff due to bumping bazel will be done with !179 (merged).

Note: Required protobuf dependencies are loaded transitively.

Pipeline: https://ci.eclipse.org/openpass/job/GtGenCore/job/MR-195