[ecashaddrjs] Use ecash: addresses in unit tests

Summary:
T3039

Convert address formats from bitcoincash: to ecash: for unit tests of cashaddr.js

Note: One bitcoincash: adddress remains, as it was manually constructed to have an improper version byte. updated to ecash: version

Test Plan: npm test and still pass

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D13474