[Cashtab] Removed isGenesisTx console.log from chronik.js

Summary: Related to T2757. Removed unnecessary console.log previously used for debugging.

Test Plan:
cd web/cashtab/src/utils
open chronik.js
at line 438, observe that the console.log has been removed

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D12408