Mobile builds are clobbering ASAN docker image

[ezyang]

The mobile builds added in #30292 reuse the ASAN docker image.

      - pytorch_linux_build:
          name: pytorch_linux_xenial_py3_clang5_mobile_build
          requires:
            - setup
          build_environment: "pytorch-linux-xenial-py3-clang5-mobile-build"
          docker_image: "308535385114.dkr.ecr.us-east-1.amazonaws.com/pytorch/pytorch-linux-xenial-py3-clang5-asan:f990c76a-a798-42bb-852f-5be5006f8026"
      - pytorch_linux_build:
          name: pytorch_linux_xenial_py3_clang5_mobile_custom_build_static
          requires:
            - setup
          build_environment: "pytorch-linux-xenial-py3-clang5-mobile-custom-build-static"
          docker_image: "308535385114.dkr.ecr.us-east-1.amazonaws.com/pytorch/pytorch-linux-xenial-py3-clang5-asan:f990c76a-a798-42bb-852f-5be5006f8026"

When this occurs, we must rename the "commit" docker image so they don't clobber each other. However, this does not appear to be happening, as discovered by @kostmo

          # Push intermediate Docker image for next phase to use
          if [ -z "${BUILD_ONLY}" ]; then
            # Note [Special build images]
            # The xla build uses the same docker image as
            # pytorch-linux-trusty-py3.6-gcc5.4-build. In the push step, we have to
            # distinguish between them so the test can pick up the correct image.
            output_image=${DOCKER_IMAGE}-${CIRCLE_SHA1}
            if [[ ${BUILD_ENVIRONMENT} == *"xla"* ]]; then
              export COMMIT_DOCKER_IMAGE=$output_image-xla
            elif [[ ${BUILD_ENVIRONMENT} == *"libtorch"* ]]; then
              export COMMIT_DOCKER_IMAGE=$output_image-libtorch
            elif [[ ${BUILD_ENVIRONMENT} == *"android-ndk-r19c-x86_64"* ]]; then
              export COMMIT_DOCKER_IMAGE=$output_image-android-x86_64
            elif [[ ${BUILD_ENVIRONMENT} == *"android-ndk-r19c-arm-v7a"* ]]; then
              export COMMIT_DOCKER_IMAGE=$output_image-android-arm-v7a
            elif [[ ${BUILD_ENVIRONMENT} == *"android-ndk-r19c-arm-v8a"* ]]; then
              export COMMIT_DOCKER_IMAGE=$output_image-android-arm-v8a
            elif [[ ${BUILD_ENVIRONMENT} == *"android-ndk-r19c-x86_32"* ]]; then
              export COMMIT_DOCKER_IMAGE=$output_image-android-x86_32
            else
              export COMMIT_DOCKER_IMAGE=$output_image
            fi
            docker commit "$id" ${COMMIT_DOCKER_IMAGE}
            time docker push ${COMMIT_DOCKER_IMAGE}
          fi

This isn't the first time this has happened; see #28581 for last time.

cc @ezyang @gchanan @zou3519 @seemethere @ljk53