Backout changes for automatically calculating the public baseurl. (#9313)

This breaks some people's configurations (if their Client-Server API
is not accessed via port 443).

synapse/handlers/identity.py

@@ -504,6 +504,10 @@ class IdentityHandler(BaseHandler):
         except RequestTimedOutError:
             raise SynapseError(500, "Timed out contacting identity server")
 
+        # It is already checked that public_baseurl is configured since this code
+        # should only be used if account_threepid_delegate_msisdn is true.
+        assert self.hs.config.public_baseurl
+
         # we need to tell the client to send the token back to us, since it doesn't
         # otherwise know where to send it, so add submit_url response parameter
         # (see also MSC2078)