[Dovecot] Set CONTROL path for shared namespace and remove index

data/conf/dovecot/dovecot.conf

@@ -175,7 +175,7 @@ namespace {
     type = shared
     separator = /
     prefix = Shared/%%u/
-    location = maildir:%%h/:INDEX=~/Shared/%%u:INDEXPVT=~/Shared/%%u
+    location = maildir:%%h/:CONTROL=~/Shared/%%u:INDEXPVT=~/Shared/%%u
     subscriptions = no
     list = children
 }