This patch enables sending the "update" ping with reason "success"
after the browser is restarted when an update is successfully applied.
MozReview-Commit-ID: 8LYxhTTrs7l
This ping will be sent as soon as an update is ready to be applied, after
it's downloaded. This is currently enabled but protected behind the
'toolkit.telemetry.updatePing.enabled' preference.
MozReview-Commit-ID: 4TuM0e5MzBl