gitaly: Deprecate bin_path and use_bundled_binaries config options

To support deployment from Git's master branch, bundled git should be the default and only supported method for Git execution in Gitaly - gitaly#6725 (closed), so in upcoming Gitaly release, we are planning to deprecate bin_path and use_bundled_binaries config options. In CNG and charts, it appears that we don't expose Gitaly's bin_path setting. Additionally, in CNG, bundled git has already been enabled by default: https://gitlab.com/gitlab-org/build/CNG/-/blob/master/gitaly/Dockerfile#L63.