Remove notify after transfer

[witter-deland]

Why remove the notify after transfer/transferFrom

Talking to untrustworthy canisters can be risky, for the following (likely incomplete) reasons:

• The other canister can withhold a response. Although the bidirectional   messaging paradigm of the Internet Computer was designed to guarantee a   response eventually, the other party can busy-loop for as long as they are   willing to pay for before responding. Worse, there are ways to deadlock a   canister.
• The other canister can respond with invalidly encoded Candid. This will cause   a Motoko-implemented canister to trap in the reply handler, with no easy way   to recover. Other CDKs may give you better ways to handle invalid Candid, but even then you will have to worry about Candid cycle bombs that will cause your reply handler to trap.