Currently we're using a custom versioning policy that creates a minor version after update.
Let's remove it and use the standard versioning policy collaborative-save.
Then we'll need to send a different version ID than the version label to the WOPI client to make sure it changes as required by Microsoft: "Please verify that your WOPI version ID changes each time the document content changes." We can use the blob digest.
PutRelativeFile for conversion
Let's use a custom versioning policy: minor version / before update.