Rollup merge of #161373 - JonathanBrouwer:ec2-local, r=Mark-Simulacrum

Allow running EC2 jobs locally

The command
```
cargo run --manifest-path src/ci/citool/Cargo.toml run-local dist-x86_64-linux
```
Fails locally with the error "Only Linux jobs can be executed locally", which I think is not correct.
The os is displayed as `ec2-x86_64ami-c8a.8xlarge-x64-linux-$github.run_id-$github.run_attempt`.
This was my hack to fix it, but I'm not sure if the problem should be fixed here or whether the os string is wrong