feat(esp_http_server): Modified the calculation of buf_len

Modified the calculation of buf_len, so that scratch buffer allocates
the memory according to requirement and not extra (except the last read chunk)

examples/protocols/http_server/simple/pytest_http_server_simple.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# SPDX-FileCopyrightText: 2018-2024 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2018-2025 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Apache-2.0
 import logging
 import os
@@ -51,11 +51,6 @@ class http_client_thread(threading.Thread):
             raise socket.timeout
 
 
-# When running on local machine execute the following before running this script
-# > make app bootloader
-# > make print_flash_cmd | tail -n 1 > build/download.config
-
-
 @pytest.mark.esp32
 @pytest.mark.esp32c3
 @pytest.mark.esp32s3