Harmonize Python shebang

Differential Revision: https://reviews.llvm.org/D83857

lldb/test/API/functionalities/plugins/python_os_plugin/operating_system.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import lldb
 import struct

lldb/test/API/functionalities/plugins/python_os_plugin/operating_system2.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import lldb
 import struct

lldb/test/API/functionalities/plugins/python_os_plugin/stepping_plugin_threads/operating_system.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import lldb
 import struct