Push subscription verification is not always executed on first install

[jonalmeida]

To avoid hitting our push servers too often, we check our last successful verification first and verify again after the PERIODIC_INTERVAL_MILLISECONDS interval.

A problem arises when we first access the prefLastVerified: if the value does not exist, we use System.currentTimeMillis() which should be fine in most cases, except on it's first usage:

private fun shouldVerifyNow(): Boolean {
    return (System.currentTimeMillis() - prefLastVerified) >= PERIODIC_INTERVAL_MILLISECONDS
}

Here, we compare the current time with the pref value (which doesn't exist), so we query the current time again. The difference of that is therefore a negative value which is always fail the verify check on that first attempt.

┆Issue is synchronized with this Jira Task