[tg bot] Better organization for unit tests

Summary:
T2972

Clean up parse.js unit tests before building rest of stack

Tests were added incrementally. As more test blocks are added, parse.js gets crowded and requires manual attention.

This diff ensures that tests are applied to all mocks.

Test Plan: npm test

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D13548