[Cashtab] [Deprecate toLegacyCash p2] Stop converting ecash addresses to bitcoincash in Send.js for one-to-many

Summary:
T2730

Depends on D12655

Stop converting one-to-many send addresses to bitcoincash: format

Test Plan:
npm start
Send a one-to-many tx

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12656