[FAB-12014] Log warning for missing index

Currently the warning is only seen in peer logs if couchdb debug is enabled.

Peer should log a warning without having to enable couchdb debug.

Log warning to peer when "no matching index found" warning comes from
couchdb queries.

Change-Id: I46a5fa663c502bbdf74261a4925ce54633384d1f
Signed-off-by: Chris Elder <chris.elder@us.ibm.com>
(cherry picked from commit 38430ad)

core/ledger/util/couchdb/couchdb.go

@@ -1074,6 +1074,10 @@ func (dbclient *CouchDatabase) QueryDocuments(query string) (*[]QueryResult, err
 		return nil, err2
 	}
 
+	if jsonResponse.Warning != "" {
+		logger.Warningf("The query [%s] caused the following warning: [%s]", query, jsonResponse.Warning)
+	}
+
 	for _, row := range jsonResponse.Docs {
 
 		var docMetadata = &DocMetadata{}