Fix getAutomaticZenRules to use proper conversion

NotificationManager was reading ZenRules from NMS and converting them directly, which means the fields added with MODES_API were not included. Switch to always convert inside of NMS instead.

Bug: 310224762
Test: atest NotificationManagerZenTest (cts)
Change-Id: I373d48cd7aee0c1fa49a8f41373cc5092d1420a4