Fixes cleanup of old alerts when stored in Clickhouse

Addresses #6066

scripts/lua/modules/alert_keys/flow_alert_keys.lua

@@ -71,6 +71,7 @@ local flow_alert_keys = {
    flow_alert_ndpi_http_suspicious_content    = 63,
    flow_alert_ndpi_dns_large_packet           = 64,
    flow_alert_ndpi_dns_fragmented             = 65,
+   flow_alert_ndpi_invalid_characters         = 66,
    -- NOTE: for flow alerts not not go beyond the size of Bitmap alert_map inside Flow.h (currently 128)
 }