ui/sched: always use Dest API

[mastercactapus]

Description:
Updates schedule on-call notifications always to use the new dest API.

Which issue(s) this PR fixes:
Part of #2639

Describe any introduced user-facing changes:
N/A

Describe any introduced API changes:
N/A

Additional Info:

• Fixed issue with dest dialogs where incorrect times were recorded when sched. TZ was different than local

[mastercactapus]

Waiting for #3779 to merge

[Forfold]

I'm not seeing a quick link appear for on-call notifications, however if I go to the link manually, it exists. It looks like we only show the link if slack or webhooks are explicitly enabled. Is this intended behavior at this point with destinations being dynamic?

        ].concat(
          // only slack/webhook supported atm, so hide the link if disabled
          slackEnabled || webhookEnabled
            ? [
                {
                  label: 'On-Call Notifications',
                  url: 'on-call-notifications',

[mastercactapus]

@Forfold It's existing behavior untouched by this work. I agree it should be changed but maybe do that in it's own PR since there may be a bit of refactoring and dialog updates to handle no valid types.

[Forfold]

Gotcha. As long as we don't lose track of it..