ui: guest stop: show overrule checkbox also if no task is active

ui: guest stop: show overrule checkbox also if no task is active

The UI state about running tasks can be out of sync, especially for
situations where one quickly follows up with a stop, e.g. after
triggering a shutdown by mistake.

So, show the checkbox always for users that got Sys.Modify on (some)
node, but pre-check it still only if there where task detected on
component creation (we could watch the state though and show a hint,
but that's a bit over the top IMO).

Show it also when HA is enabled but explicitly disable it there,
hopefully this increases the chance that the users can understand that
this is done by design, and isn't a bug – ideally we would also show
an extra hint.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>