Wrong umask for ubuntu user on self-hosted runners

[guicaulada]

The umask for the ubuntu user is 0002 when it should be 0022 to match what we have for the runner user on GitHub-hosted runners.

This can be fixed with user-data, I believe GitHub also handles the creation of this runner user through user-data, we might want to investigate more details of the runner user and replicate the same user on our end to ensure all behavior matches.