Close ZenModeScheduleRuleSettingsActivity when rule is deleted

This fixes an issue where the ZenRuleButtonsPreferenceController was redirecting to the rule list, but the container fragment was still trying to refresh the rule, leading to a "rule not found" toast. This also makes the transition look nicer, as it's a "back" instead of a "forward" animation now.

Fixes: 244103559
Test: Manually on phone & tablet
Change-Id: Ie26511dcaec4c7976f488936cdc6d417110ca1b1