staging: Deploy swh.loader.svn v1.0.0

Contains:

• performance gain
• T611: svn:external support

Plan:

• Deploy package

• Restart service swh-worker@loader_svn and swh-worker@loader_high_priority

• Trigger scheduling of save code now on known origins with externals

• T3870: Analyze results [1]

• [1] logs: http://kibana0.internal.softwareheritage.org:5601/goto/3478f6c5dd9f9662ce3eccdd6b9ac169

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Migrated from T3864 (view on Phabricator)