remove minimum total fee option

Summary:
Backport of Core PR10390
https://github.com/bitcoin/bitcoin/pull/10390/files

Completes T522

Test Plan: bitcoin-qt removes the total radio button option as expected.

Reviewers: deadalnix, Fabien, #bitcoin_abc, Mengerian

Reviewed By: Fabien, #bitcoin_abc, Mengerian

Subscribers: markblundeberg, Mengerian, teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2322