MT#4369 Disable Timestamp search on Callflows

this created "min(timestamp) LIKE %search%" which is not valid SQL

lib/NGCP/Panel/Controller/Callflow.pm

@@ -21,7 +21,7 @@ sub root :Chained('/') :PathPart('callflow') :CaptureArgs(0) {
     my ( $self, $c ) = @_;
 
     $c->stash->{capture_dt_columns} = NGCP::Panel::Utils::Datatables::set_columns($c, [
-        { name => "timestamp", search => 1, title => "Timestamp", literal_sql => "min(timestamp)" },
+        { name => "timestamp", search => 0, title => "Timestamp", literal_sql => "min(timestamp)" },
         { name => "call_id", search => 1, title => "Call-ID" },
         { name => "caller_uuid", search => 1, title => "Caller UUID" },
         { name => "callee_uuid", search => 1, title => "Callee UUID" },