[#83716736] Update mms backup & monitoring agents

- Change package install procedure
- Add more tests
- Add cibuild script shenanigans
Yeap. From the Gemfile.lock it's a dep of this version of chefspec:
```
    chefspec (4.0.2)
      chef (~> 11.12)
      fauxhai (~> 2.0)
      rspec (~> 3.0)
```

I was just trying to get rid of the annoying deprecation message. Had to tweak the rspec command run too.