Add a warning and override requirement for installations with default partition schemes
Description of problem:
Currently, we do not have a way to prevent a user of Satellite 6 from filling up their partitions with database or pulp data, and we do not enforce explicit partitioning schemes to help prevent issues with bleed-over of over-syncing causing a user to fill up a partition which results in database corruption.
Proposal is to implement a a override-able warning into the installer that prevents initial run of the installer when items for postgres, mongo, and pulp are all found to be under the same partition with no division (i.e. /var).
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. You can install with any partition scheme.
2. You can fill up /var with data from pulp and corrupt your database content.
Caseload resulting from unknowingly breaking Satellite due to space issues
We should warn users of a best practice scenario and make them acknowledge that they are at risk for corrupting their data because of a non-divided partitioning scheme.
Related to RHBZ 1435420