Drop mock_get_scheduler which creates indirection for no good reason

This is no longer useful, as removing it and tests are still ok.

Test Plan

tox

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Migrated from D4287 (view on Phabricator)

Build is green

Patch application report for D4287 (id=15157)

Rebasing onto 2ff92ef4...

Current branch diff-target is up to date.

Changes applied before test

commit 30ad6200a2bfaed4fd472c5343411703259baf82
Author: Antoine R. Dumont (@ardumont) <ardumont@softwareheritage.org>
Date:   Fri Oct 16 14:30:54 2020 +0200

    Drop mock_get_scheduler which creates indirection for no good reason
    
    This is no longer useful, as removing it and tests are still ok.

See https://jenkins.softwareheritage.org/job/DLS/job/tests-on-diff/55/ for more details.

Merge request was merged

closed