Fixes based on feedback from Builders Plan run throughs

TL;DR

Fixes issues identified during engineeering team Builders Plan run throughs

Address feedback where the lab checks for a specific customer email but doesn't say what it is. Builds on @diaomwiggins change.
Fixes known issue where cleanup scripts can fail in some scenarios
Updates language in "Distributing Your Applcation with Replicated" to account for the customer email being set already.
Allows the user to validating the install from the customer perspective after the preflights lab