We do this since we are yet to figure out how the entire realm
internal bots scenerio should work and therefore for the timming
we will use notification bot to deliver the reminders.
A key part of this is the new helper, get_user_by_delivery_email. Its
verbose name is important for clarity; it should help avoid blind
copy-pasting of get_user (which we'll also want to rename).
Unfortunately, it requires detailed understanding of the context to
figure out which one to use; each is used in about half of call sites.
Another important note is that this PR doesn't migrate get_user calls
in the tests except where not doing so would cause the tests to fail.
This probably deserves a follow-up refactor to avoid bugs here.
We add conditional infinite sleep to this delivery job as a means to
handle case of multiple servers in service to a realm running this
job. In such a scenerio race conditions might arise leading to
multiple deliveries for same message. This way we try to match the
behaviour of what other jobs do in such a case.
Note: We should eventually do something to make such jobs work
while being running on multiple servers.