Remove `ignore_providers` option

COUCHDB-2796
diff --git a/src/couch_index_plugin.erl b/src/couch_index_plugin.erl
index 9707089..48822ed 100644
--- a/src/couch_index_plugin.erl
+++ b/src/couch_index_plugin.erl
@@ -42,4 +42,4 @@
 
 update(Handle, State, View, Updated, Removed) ->
     Args = [State, View, maybe_transform(Updated), maybe_transform(Removed)],
-    couch_epi:apply(Handle, ?SERVICE_ID, index_update, Args, [ignore_providers]).
+    couch_epi:apply(Handle, ?SERVICE_ID, index_update, Args, []).