Add tests for commands that are used by our cloud

[aljazerzen]

Commands that cloud uses but are not tested:

• gel query --output-format tab-separated ...
• gel list branches
• query --file ...

https://github.com/geldata/nebula/blob/c9c564c450afe4370af11dcd6c21cb7c2a7bb625/cmd/nebula/server/platform/jobspec/edgedb/upgrade.nomad#L111