Draft: ci: test pipeline performance

Running locally (MacBook M2 Pro), //localhost:test takes 1.2s:

$ podman run \
          --cpus 4 \
          --memory 4G \
          -v $PWD:/mnt/src \
          -w /mnt/src \
          --rm \
          -it registry.gitlab.arm.com/ci/component/bazelisk:1.0.1 \
          sh -c 'cd e2e; bazelisk test //...'

Running on CI runner, //localhost:test takes 14.5s:

test:
  stage: test
  image: registry.gitlab.arm.com/ci/component/bazelisk:1.0.1
  tags:
    - arm64
  script:
    - cd e2e; bazelisk test //...

Running on CI runner with parallel jobs, //localhost:test takes 20-50s:

test:
  stage: test
  image: registry.gitlab.arm.com/ci/component/bazelisk:1.0.1
  tags:
    - arm64
  parallel:
    matrix:
      - FOO: [1, 2, 3]
        BAR: [4, 5, 6]
  script:
    - cd e2e; bazelisk test --test_env=FOO=${FOO} --test_env=BAR=${BAR} //...

On our normal pipeline set up, we've seen it take 70.1s.