Follow-up to https://github.com/jupyterhub/kubespawner/pull/735#discussion_r1254129852, if a profile_option is configured to have unlisted_choice.enabled to True, but choices is not set, we currenlty show a dropdown with just 'Other' as an option. This is kinda ugly. Instead, it should just not show the dropdown at all.
Follow-up to https://github.com/jupyterhub/kubespawner/pull/735#discussion_r1254129852, if a profile_option is configured to have
unlisted_choice.enabledtoTrue, butchoicesis not set, we currenlty show a dropdown with just 'Other' as an option. This is kinda ugly. Instead, it should just not show the dropdown at all.