fix checking the now boolean prompt response

fix checking the now boolean prompt response

When the prompt abstraction got added in bc05a8f ("add basic UI
plugin infrastructure") it also inlined the check for the answer, as
that can be differently structured for each user interface, and
returns bool. But when switching over to this new infra, two sites
weren't updated to the simpler bool check and still checked with the
previous "equals 'ok'", which now was always false.

Fixes: 72bea99 ("switch prompt, error and message calls to new UI infra")
Reported-by: Alexander Zeidler <a.zeidler@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>