AllWatcher doesn't dispatch public address changes

[Simon Richardson]

The AllWatcher doesn't dispatch the public address changes as there is a race when settings the information in the database.

Essentially, the units are updated before the machine and the AllWatcher can't retrigger a new delta based on the fact that the machine is updated for the child units. So to get the new delta you have to trigger a unit change to get the public address change.

This relates to https://github.com/juju/python-libjuju/issues/551

[John A Meinel (jameinel)]

So this is blocking Openstack from moving to 2.9 which impacts them being able to test things like Impish and Jammy support, so we need to be prioritizing it for them.

[Simon Richardson (simonrichardson)]

The workaround, for now, is to query the application facade from pylibjuju[0].
There is still some work to do on the juju side:

 - Remove the Public and Private address from the Unit delta on the all watcher.
 - Possibly provide a way to allow entity dependencies (machine - units for instance) to trigger a new entity delta emission when there is a cross-cutting concern.

0: https://github.com/juju/python-libjuju/pull/600