[az][gui] Inconsistent Zone selector in the 'Configure instance' page

Describe the bug Depending on the state of the UI and the system, the 'Configure instance' page does not show the same options in the 'Zone' label.

• 'Enable all zones' is present only if all 3 zones are disabled, even if that could make sense with two zones.
• The selector is disabled if all 3 zones are enabled, so I cannot select the zone I wish for it and enable on that one.
• If I already had a 'Configure instance' page open before disabling all zones, then the initial set zone is still selected in the disabled widget, and I now have the 'Enable zone X' option.

To Reproduce How, and what happened?

1. Open the 'Launch and Configure' page
2. Then go into the 'All Instances' page and disable some/all zones
3. Then go back to the Catalogue tab.

Expected behavior Ideally, the state of that button should be easier to predict. For instance, either unavailable zones are always selectable, or never selectable (imo, the first option would be better, so that the user is still able to enable just the zone they want to put their VM). Same for the 'Enable all zones', it would be nice to have the button available as soon as there's one zone that's not enabled. Alternatively, would it be possible to create a VM inside an unavailable zone? It doesn't make sense to have that in real life, but for prototyping purposes, it avoids having to enable the zone with all the started VMs in it (there's some loading when doing that).

Logs Please provide logs from the daemon, see Access logs on where to find them on your platform.

Additional info

• OS: Win 11 Pro
• CPU architecture or model: x64
• multipass version multipass 1.17.0-dev.ci6331+ga58dcf2e.win multipassd 1.17.0-dev.ci6331+ga58dcf2e.win

Additional context Note: I was not sure whether to register this as a feature request or as a bug...