(ci: fix build master) scheduler.tests: Adapt model according to latest change

origin model no longer allows to have type.

This fixes the current master build [1]

Related to f533f62bbf114cfcc29f7c72307c4dfbe99cf048

Similar to swh-journal!138 (closed) Related to swh-model!90 (closed)

• [1] https://jenkins.softwareheritage.org/job/DSCH/job/tests/808/console

Test Plan

tox

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Migrated from D2899 (view on Phabricator)