[Cashtab] Patch address input height in Send.js

Summary: Related to T2794. The ExpandingInputAddressCtn height property was too high, requiring users on smaller screened devices to scroll to see the send button. The ctn's height has been reduced so that the send button is visible without scrolling on smaller screens.

Test Plan:
cd web/cashtan && npm start
using dev tools, set the browser's view to mobile
select a device with a small screen from the device list

• iPhone SE or Galaxy fold are good options

observe that the send button is visible by default, and when the input has been switched to MultiRecipient.

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D12609