[ecash-herald] Implement chronik-client 0.9.0 with failover proxy

Summary: Upgrade to chronik-client with automated backup servers. Remove startup bailout on failed connection, an artifact of manual deployments and no support for backup chronik.

Test Plan:
npm test
node index.js and msgs are broadcast to telegram bot info in local secrets.js

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14869