ci: fix directory to discover quickstarts (#9931)
ci: fix directory to discover quickstarts (#9931)

The intention was to discover the quickstarts available using the
`google-cloud-cpp` version in the `**/quickstart/WORKSPACE.bazel`
files.  To do so, we should run the bazel query in a `**/quickstart`
directory.
googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp