[Cashtab][Alias] Deprecate alias specific BlockConnected websocket events

Summary:
See T3216 for background

Cashtab no longer needs to cache aliases and alias tx histories, therefore there is no need for processChronikWsMsg to be listening on BlockConnected events to refresh local alias cache on new blocks.

There is currently no other uses for 'BlockConnected' events in Cashtab.

Test Plan:
npm test
npm start
enable the aliasSettings.aliasEnabled flag in Ticker.js (will be moved in subsequent diff)
open console log and ensure no websocket errors upon new block found as the event should no longer be picked up
disable the aliasFlag, reload cashtab and ensure no websocket errors in console log upon startup

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D14184