Tidy up Makefile, docker compose files, etc.

[toph-allen]

The Makefile contains targets whose names are unclear, possibly duplicated, or no longer used. None of them are used by CI.

• connect-up / connect-down
  • Adds containers to a network (.github/local/make-network.yml)
  • Uses inst/ci/test-connect-lic.yml, which is the CI compose file
• test-env-up / test-env-down
  • Uses .github/local/test-connect-ci.yml (which is not the CI compose file)
  • Also uses make-network.yml
• mail-up / mail-down
  • Don't seem to be used anywhere?
  • Use .github/local/mail.yml
• test / test-run / test-run-i
  • Seem to reference an old & broken workflow, can probably be deleted.
  • Reference test.yml

Compose files

• inst/ci/test-connect-lic.yml creates a single service named connect with scale: 2. Used in CI.
• .github/local/test-connect-ci.yml creates two services, connect1 vs connect2. Not used in CI.
• .github/local/mail.yml
• test.yml — Creates a container that runs a file /test/inst/ci/run_tests.R that doesn't exist (seems to have been moved to .github/local/run_tests.R.