Extract build check into class

[finishes #53504907]

* Use Rake task arguments to set the server and job name to check but
  have working (internal) defaults.
* Remove environment variables.
Increase the snapshot timeout on AWS

[finishes #53253461]

Snapshots on AWS can take a long time (> 30m) for large disks that are
in heavy use. Increasing the time that we wait because we were seeing
successful snapshots in the AWS console that BOSH said were failing.