bitbucket: Fix full lister with fallback [start, end] if not provided

It nows starts without failing. It encounters the same behavior as the incremental one though (cf. #1826 (closed)). The fix for that behavior is on its way and out of the scope of this diff.

Related #1826 (closed) Depends on !74 (closed)

Test Plan

• tox
• docker-dev: schedule list-bitbucket-full (check swh-lister's logs)

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Migrated from D1629 (view on Phabricator)