GUI: Receive: Remove option to reuse a previous address
This was justified by the need to "resent" an invoice, but now that we have the request history, that need should be gone.
Under the receive tab, there should be no option to reuse an existing receiving address.
Reviewers: jasonbcox, deadalnix, Fabien, O1 Bitcoin ABC, #bitcoin_abc
Reviewed By: jasonbcox, O1 Bitcoin ABC, #bitcoin_abc
Differential Revision: https://reviews.bitcoinabc.org/D2805