Vault: Migrate data from old vault to new one

Vault got migrated (alongside its db) but not the cooked data.

Decide whether we want to keep it or not. And then move it.

Implementation wise, there are 2 possibilities (maybe more?):

cook back all that has been cooked (using the existing vault db's data)
implement scripts that reads from the old pathslicing objstorage and copy to the new azure objstorage (@douardda has some benchmark experimentation tools that can help there).

Migrated from T1757 (view on Phabricator)