out_logdna: remove promoted keys from line field

Signed-off-by: lecaros <lecaros@chronosphere.io>

Author: lecaros

tests/runtime/out_logdna.c

@@ -695,6 +695,14 @@ void flb_test_backward_compat()
  * Test: repeated start/push/stop/destroy cycles to verify
  * proper resource cleanup (no crashes from leaks or double-free).
  */
+static void cb_lifecycle_noop(void *ctx, int ffd, int res_ret,
+                              void *res_data, size_t res_size,
+                              void *data)
+{
+    flb_sds_t json = res_data;
+    flb_sds_destroy(json);
+}
+
 void flb_test_lifecycle()
 {
     int i;
@@ -718,6 +726,9 @@ void flb_test_lifecycle()
                        "api_key", "test-key",
                        NULL);
 
+        flb_output_set_test(ctx, out_ffd, "formatter",
+                            cb_lifecycle_noop, NULL, NULL);
+
         ret = flb_start(ctx);
         TEST_CHECK(ret == 0);