Really destroy models with '--force' - LP:1884557

Without '--force' to 'destroy-model', models can be stuck in
'destroying' as Juju waits for application hooks to successfully
finish firing. Unfortunately, hooks can fail for various reasons[1].

[1]https://paste.ubuntu.com/p/nYHnGpX4sS/



Reviewed-on: https://code.launchpad.net/~hloeung/mojo/force-destroy-model/+merge/388105
Reviewed-by: Stuart Bishop <stuart.bishop@canonical.com>