cubicweb #1417110 postcreate.py must fire hooks by default [validation pending]

See also https://www.cubicweb.org/ticket/1412648

As developer, I need postcreate.py to behave as any script launched with cubicweb-ctl shell wrt to hooks : the default behavior must be to execute all the hooks, especially the hooks which check the cardinalities, but not only. Otherwise it's very easy to end up with an invalid initial database, and have no idea that this happened. If a developer needs to disable some hooks in postcreate.py he has to explicitely disable them.

priorityimportant
typebug
done in3.15.0
load0.200
load left0.000
closed by#1d1cfc97f6b9 [migration] fire hooks in postcreate by default (closes #1417110)