Make manually activated rules stay activated on reboot

For symmetry with the old behavior of snoozing, we were clearing activation state on reboot. However users apparently expect modes to stay on, so do that.

Manual deactivation is still not stored, and cleared on reboots.

Fixes: 367309333
Test: atest ZenModeHelperTest + manual
Flag: android.app.modes_ui
Change-Id: I40c92d49d5a5cae5fe4810a8a9f95de0d0035c3e