(maint) Cleanup specs for the `module` Face’s `install` action.

Prior to this change, the specs relied on a fragile chain of stubbed
expectations, which changes elsewhere in the application have rendered
incorrect and non-operational.

This change aims to improve these specs by stubbing less and making
more robust assertions about the data.
Merge pull request #2898 from pvande/maint/stable/cleanup-module-install-spec

(maint) Cleanup specs for the `module` Face’s `install` action.