[flashing scripts] [ESP32] Fix running esptool.py (#30627)

In Espressif IDF 5.x, esptool.py changed from a script under $IDF_PATH to an
installable Python package (#27060). This change udpates the flashing script
accordingly.

scripts/flashing/esp32_firmware_utils.py

@@ -86,7 +86,7 @@
  # Tool configuration options.
  'esptool': {
  'help': 'File name of the esptool executable',
- 'default': None,
+ 'default': 'esptool.py',
  'argparse': {
  'metavar': 'FILE',
  },
@@ -103,9 +103,8 @@
  """\
  Unable to execute {esptool}.
 
- Please ensure that this tool is installed and
- that $IDF_PATH is set. See the ESP32 example
- README for installation instructions.
+ Please ensure that the esptool Python package is available.
+ See the ESP32 setup guide for instructions.
  """,
  },
  'parttool': {
@@ -308,7 +307,6 @@ def read_sdkconfig(self, filename):
  return result
 
  IDF_PATH_TOOLS = {
- 'esptool': 'components/esptool_py/esptool/esptool.py',
  'parttool': 'components/partition_table/parttool.py',
  }