[tg bot] standardize line breaks between conditionally rendered sections

Summary:
T2972

Depends on D13299

Make sure Telegram msgs never end with a line break. Make sure all conditionally rendered Telegram msg sections start with two line breaks.

Test Plan:
npm test
npm run msgs and confirm line breaks between telegram msg sections

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D13300