Remove python bin declaration in switcher script

This removes non-hermetic python usage and instead follows the
recommendation of relying on the hermetic version of python packages
embedded in the Android source tree (which is already turned on via
python2 declaration in Android.bp).

Bug: 185904737
Test: m -j 8 ds-docs-switched, and verify that output before and after
matches

Change-Id: Ia831fbcff4c333aeaf7da6ca5a9af576f15079ac
diff --git a/switcher4.py b/switcher4.py
index 7e06fac..6cd7739 100644
--- a/switcher4.py
+++ b/switcher4.py
@@ -1,5 +1,3 @@
-#!/usr/bin/python
-#
 # Copyright 2019 - The Android Open Source Project
 #
 # Licensed under the Apache License, Version 2.0 (the "License");