clear pulp3's checksum values on its yum repository objects
as part of a pulp3 upgrade, pulp is setting the checksum values metadata_checksum_type & package_checksum_type on the REPOSITORY object (Not publications). This can cause a problem to occur later on, especially with pulp capsule syncs.
On upgrade we should clear these values.
Fixes #33567 - remove checksum values from pulp3 repos
due to an upgrade bug in pulp3, repository objects can have a checksum set
which will cause the checksum to be used when publishing metadata. This
causes a problem with pulp2 smart proxies syncing content and expecting
all package checksums to match the metadata checksums