memory.gitlab-ci.yml

This includes several changes:
  - Rename memory-static to generate-gems-size-metrics-static
  - Rename memory-static-objects to generate-gems-memory-metrics-static
  - Change generate-gems-size-metrics-static interface. The script now
    expect `bundle exec derailed bundle:mem` output as its input. The
    script output to stdout, or stderr for error message.
  - Change generate-gems-memory-metrics-static interface. The script now
    expect `bundle exec derailed bundle:objects` output as its input.
    The script output to stdout, or stderr for error message.
  - Generate gem size metrics. Script generate-gems-size-metrics-static
    extract each gem size from `bundle exec derailed bundle:mem` output.
    Save output to metrics file in format: 'gem_size_mb{name="zip"} 0.5'