Seems odd to use CI_USE_APT_INSTALL == no as an alias for CI_OS_NAME == macos. Fix this by removing the alias.
Also, for github CI:
- restore MAKEJOBS to the same value as in cirrus.yml.
- remove cirrus-only PACKAGE_MANAGER_INSTALL.
- remove redundant TEST_RUNNER_TIMEOUT_FACTOR
- Add M1 link