Running the Android emulator is not currently supported on CircleCI, since it's not supported by the type of virtualization CircleCI uses on Linux. Some users have reported success with Android emulators on the macOS executor, but there are many caveats and success with route depends on your application. Therefor we cannot provide support assistance for users attempting this route, and we recommend using an external service such as Firebase Test Lab to run your emulator tests from your CircleCI job.
The gcloud tools are preinstalled on the CircleCI Docker images for Android - see the Dockerfiles here and Docker Hub links here.
There is an open feature request for this feature. Adding your vote will increase the likelihood of this feature coming to CircleCI in the future.