Update titles and summaries of the Date and time settings page

Design doc: go/dd-android-settings-time-2024

This change covers Part 1, which consists of adding user-friendly summary under each toggle and rewording titles.

Bug: 296835792
Test: on-device and atest
Flag: EXEMPT resource only update
Change-Id: I0b685743599880fc1c4ad680eca9c36e4e64d0ff