[mock-chronik-client] Clean up test mocks file

Summary:
The mocks are somewhat generated but the file should still be reviewed.

• Any changes to tests should have typed mocks that match new tests
• We had garbage and lint issues in this file that was missed from the generated tag

Test Plan: proofread, CI tests still pass

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17543