Improve automation of RC testing on real world databases

See also: https://pad.riseup.net/p/civi-distributed-test-upgrades

== Background ==

The normal QA process involves running test upgrades with sample data from https://github.com/civicrm/civicrm-upgrade-test . However, this sample data is not very diverse.

From time-to-time, we've discussed the idea of creating anonymized/munged databases, but there's always pushback on the anonymization mechanism.

== Approach ==

For this issue, we're taking a distributed approach to testing. When a new release-candidate (RC) becomes available, a downstream server should respond to it automatically – clone a realistic database, attempt the upgrade, and report the success or failure (w/messages).

This is not intended for consumption by all sites – but if we can get a handful from different integrators, that will be an improvement in our coverage.