Analyze and make the bitbucket ingestion faster

It's apparently [1] often flushing new objects to add to the storage. So a bump in the buffer configuration should help [2].

Also lots of time is spent running the to_model/from_dict [1] stanza. As most of the cpu are usage full [3] bumping the machine's cpus to something higher should help.

• [1]

• [2]

• [3] https://grafana.softwareheritage.org/goto/AQRE2mInk?orgId=1

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Migrated from T3563 (view on Phabricator)