Track periodic and flex intervals in ScheduledJobStateChanged events

Added logging of periodic and flex intervals for
ScheduledJobStateChanged events. This data will help analyze app
usage of periodic job APIs and identify potential optimization
opportunities for performance and power.

Bug: 296629905
Test: Ran "statsd_testdrive 8". New fields added to the
ScheduledJobStateChanged are retrieved shown without any errors.

Change-Id: Ib41ea3edfb9d22772206f16975ce3a2d287cbbfd