processor_labels: Remove a needless existence check for insert operation

Insert implies that adding new key-value pairs of labels.
However, we did put the existence check for the keys of labels.
This shouldn't be effective for such operation.

Signed-off-by: Hiroshi Hatake <hiroshi@chronosphere.io>

plugins/processor_labels/labels.c

@@ -1524,26 +1524,27 @@ static int insert_labels(struct cmt *metrics_context,
                                                         pair->key);
 
         if (result == FLB_TRUE) {
-            result = metrics_context_insert_dynamic_label(metrics_context,
-                                                          pair->key,
-                                                          pair->val);
+            continue;
+        }
 
-            if (result == FLB_FALSE) {
-                return FLB_FALSE;
-            }
+        result = metrics_context_insert_dynamic_label(metrics_context,
+                                                      pair->key,
+                                                      pair->val);
+
+        if (result == FLB_FALSE) {
+            return FLB_FALSE;
         }
-        else {
-            result = metrics_context_contains_static_label(metrics_context,
-                                                           pair->key);
 
-            if (result == FLB_FALSE) {
-                result = metrics_context_insert_static_label(metrics_context,
-                                                             pair->key,
-                                                             pair->val);
+        result = metrics_context_contains_static_label(metrics_context,
+                                                       pair->key);
 
-                if (result == FLB_FALSE) {
-                    return FLB_FALSE;
-                }
+        if (result == FLB_TRUE) {
+            result = metrics_context_insert_static_label(metrics_context,
+                                                         pair->key,
+                                                         pair->val);
+
+            if (result == FLB_FALSE) {
+                return FLB_FALSE;
             }
         }
     }