`gitlab-runner run-single` requires all configuration parameters to be specified on the command-line. Aside from security issues like #37511, this is also inconvenient for people configuring `gitlab-runner`s that are partially executed via `run-single` and partially via `run`. This could be fixed by adding two CLI parameters to `run-single`, namely `--config-file` for specifying which config.toml to use (defaulted to `.gitlab/config.toml`) and `--config` or `--runner-name` choosing which runner config from this config file to use to initialize the config. I will start working on this soon, it will supersede !4755 and fix #37511