[Cashtab] [Extension] [Code cleanup p3 retry] Remove commented out testing code from background.js

Summary:
T2751

Depends on D12544

This commented out code is leftover from testing a past diff and should not be in the codebase. Removed.

Test Plan: Confirm only comments removed

Reviewers: #bitcoin_abc, kieran709

Reviewed By: #bitcoin_abc, kieran709

Differential Revision: https://reviews.bitcoinabc.org/D12545