This fixes a regression in 93678e89cd
and a4979410f9, where the webhooks using
authenticated_rest_api_view were migrated to a new model that didn't
include setting a custom Client string for the webhook.
When restoring these webhooks' client strings, we also fix places
where the client string was not capitalized the same was as the
product's name.
These are the straightforward ones.
Note that there is a line in zerver.lib.test_classes.build_webhook_url
that lost test coverage. That's because most of our tests test using
stream messages so the webhook URLs being tested always have a query
parameter. So the line that accounts for there being no query
parameters never gets called, which is fine, but we should still
keep it.
This commit migrates all webhooks to use check_send_stream_message
instead of check_send_message. The only two webhooks that still
use check_send_message are our yo and teamcity webhooks. They
both use check_send_message for private messages.