Reconciler causes SLO manifests to loose their bytes in bucket listings

[clayg]

When the reconciler needs to move a SLO manifest to a different policy the InternalClient it uses forgets to set the req.environ['swift.content_type_overridden'] so the SLO magic `;swift_bytes=XXX` in the Content-Type gets sanitized out. The result is the object PUT doesn't update the bucket listing bytes from the Content-Type record the same way SLO normally does so your listing shows the manifest size which is "incorrect" from the s3api standpoint and inconsistent with the normal Swift SLO API behaviors.

I actually found this issue because of an unrelated s3api bug that made wrong-policied maifests quite common:

https://review.opendev.org/c/openstack/swift/+/866508/1

... but the problem is exists for any natual split brain scenario where manifests need to get moved by internal client.