Repeating reminders first sent in a different tz will have incorrect repeat length

If a reminder is sent in one tz, and it's notification will be sent in a different tz ( eg daylight savings ), we calculate if this is a into or from DST transition and subtract/add an hour accordingly.

However, for repeating reminders, this code is never run again. And so repeating reminders have their length set an additional hour in either direction to account for that first tz change.

Start by tracing the reminder scheduling path for repeating reminders and the existing daylight-saving-time adjustment described in the issue. Compare the initial notification calculation with later repeats, then verify that repeats retain the correct duration when the sender and notification time zones cross a DST transition.

Written by the indexing model from the issue text.