paxos: fix trimming when we skip over incrementals
paxos: fix trimming when we skip over incrementals

Remove open-coded trimming of old states and use our method (that also
removes additional per-state files).  Fixes old stray state files.

Signed-off-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph