fix: Use delete instead of free for SQLite3_result in load_mcp_query_rules_to_runtime

Change free(resultset) to delete resultset in
ProxySQL_Admin::load_mcp_query_rules_to_runtime.

SQLite3_result is a C++ class allocated with new, so it must be
deallocated with delete, not free(). Using free() causes undefined
behavior and memory leaks.

Addresses coderabbitai review comment.

lib/ProxySQL_Admin.cpp

@@ -7789,7 +7789,7 @@ char* ProxySQL_Admin::load_mcp_query_rules_to_runtime() {
 
 	if (success == false) {
 		if (resultset) {
-			free(resultset);
+			delete resultset;
 		}
 	}