In the deposit, the swh_anchor_id is now of the form:
swh:1:dir:<hash>;?origin=<origin>;visit=<snp-hash>;...
Where it was of the form:
swh:1:dir:<hash>;?origin=<origin>
This adapts the extraction to take into account the new format and provide the
`end` of the data.slice call.
Related to T1398
Related to T2409