[Cashtab] [chronik tx history p14]Remove legacy tx parsing functions, tests, and mocks

Summary:
T2447

Depends on D12139

Remove all legacy tx history parsing functions associated with the bch-api approach. Also remove their related unit tests and mocks.

Test Plan:
Review removed functions. grep -r <functionName> src/ for each to confirm they are not used anywhere else in the codebase.

npm start and app still works

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D12140