[Cashtab] Cleaner state setting in activateWallet

Summary:
Configure in App.js still had some dead code routines passed in as loader handlers. Remove.

Make indices more robust in .map wallet render to prevent duplicate key

Better state setting in activateWallet

Test Plan: npm test

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D15669