annotate.c: possible fix for proxy-only mailbox annotations (e.g. /server)
Revert "annotate.c: possible fix for proxy-only mailbox annotations (e.g. /server)"

This was a shot in the dark and either incomplete or totally bogus

This reverts commit fe0ab49504dfa4c346bfa10796887a0003fb4bd5.
[mupdate] Fix MUPDATE communication about mailboxes, servers,
partitions, locations and access control lists

    The so-called 'server' is not actually a 'server', but more like a
    'location' (since it definitely includes the partition, but not
    always the server).

    Avoid confusing use of terminology like that. These structs have
    servers and partitions for the purposes of IMAP, and for MUPDATE,
    all that the RFC leaves us room for is locations.