esp-tls: mark esp_tls_conn_delete API as deprecated

It is recommended to use `esp_tls_conn_destroy` API instead

examples/protocols/https_x509_bundle/main/https_x509_bundle_example_main.c

@@ -72,7 +72,7 @@ static void https_get_task(void *pvParameters)
                 ESP_LOGE(TAG, "Could not connect to %s", web_urls[i]);
             }
 
-            esp_tls_conn_delete(tls);
+            esp_tls_conn_destroy(tls);
             vTaskDelay(1000 / portTICK_PERIOD_MS);
         }