Update timings.json

Summary:
Cleanup after test renaming.

Depends on D2381

Test Plan:
Read the timings.json file and ensure that:

• all the tests are present
• only the existing tests are present

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2382