Name implicitly created CHECK constraints

to ease future maintenance work. The pattern for catching the right
CHECK constraint is admittedly vague but the order in which auto-created
CHECK constraints of a table is removed doesn't really matter assuming
the update is always completed before another update is applied. If
updates are run through Update.php, that should be always the case.

Furthermore eliminating a bug causing application of several patches each
time when running Update.php

Bug: 65757
Bug: 65813
Change-Id: Ic7fc3bd836241dce8f296237bbd80ed3e4d1ee0d