Is it possible to set the SSH auth from config.toml?

Is it possible to set the username and password to use for SSH from `config.toml`? I imagine setting `environment` might work, but I'd like them to not leak into the actual runner environment at that point. Can they be scrubbed somehow?

Start by locating how config.toml is parsed and where the executor configures SSH credentials for GitLab Runner jobs. Trace whether values reach the runner environment, then define a configuration path that keeps them scoped away from that environment and verify the behavior with the relevant executor tests.

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