misc(test): use php' native syslog priority consts

Author: burgesQ

testdata/logging.php

@@ -1,10 +1,10 @@
 <?php
 
-frankenphp_log_message("testing emerg as ERROR", 0);
-frankenphp_log_message("testing alert as ERROR", 1);
-frankenphp_log_message("testing crit as ERROR", 2);
-frankenphp_log_message("testing error as ERROR", 3);
-frankenphp_log_message("testing warning as WARN", 4);
-frankenphp_log_message("testing notice as INFO", 5);
-frankenphp_log_message("testing info as INFO", 6);
-frankenphp_log_message("testing debug as DEBUG", 7);
+frankenphp_log_message("testing emerg as ERROR", LOG_EMERG);
+frankenphp_log_message("testing alert as ERROR", LOG_ALERT);
+frankenphp_log_message("testing crit as ERROR", LOG_CRIT);
+frankenphp_log_message("testing error as ERROR", LOG_ERR);
+frankenphp_log_message("testing warning as WARN", LOG_WARNING);
+frankenphp_log_message("testing notice as INFO", LOG_NOTICE);
+frankenphp_log_message("testing info as INFO", LOG_INFO);
+frankenphp_log_message("testing debug as DEBUG", LOG_DEBUG);