ReplicatedPG: use pending_attrs in rollback

Otherwise, we won't have the correct attr_cache in make_writeable.

Fixes: #7663
Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG: clear cached_attrs in apply_pending_attrs, not _delete_head

We need the old cached_attrs in make_writeable for the clone, so don't
update cache_attrs until we are submitting the transaction.

Fixes: #7663
Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG: adjust pending attrs correctly in copy_from

Otherwise, subsequent reads might not get the correct cached attrs.

Fixes: #7663
Signed-off-by: Samuel Just <sam.just@inktank.com>
Merge remote-tracking branches 'upstream/wip-div' and 'origin/wip-7663' into wip-sam-testing