The V5 protocol sends a minimum_wait_duration per table, but we only
use the duration of the last table to schedule the next update, which
could be wrong if the duration is longer or shorter than others.
This patch fixes this issue. The nextUpdateTime pref will contain the
earliest update time among updated tables. And we use per-list pref to
store the update time for tables that have later time than the earliest
table. We schedule the timer according to the earliest update time and
skip those tables that are not expired.
We also updates relevant tests for this change.
Differential Revision: https://phabricator.services.mozilla.com/D323990
Tim Huang
57cf7b17da