ardupilotwaf: drop subprocess monkeypatching for unsupported Python

Not needed now that minimum Python is 3.8.

wscript

@@ -20,49 +20,6 @@ import glob
 from waflib import Build, ConfigSet, Configure, Context, Utils
 from waflib.Configure import conf
 
-# Ref: https://stackoverflow.com/questions/40590192/getting-an-error-attributeerror-module-object-has-no-attribute-run-while
-try:
-    from subprocess import CompletedProcess
-except ImportError:
-    # Python 2
-    class CompletedProcess:
-
-        def __init__(self, args, returncode, stdout=None, stderr=None):
-            self.args = args
-            self.returncode = returncode
-            self.stdout = stdout
-            self.stderr = stderr
-
-        def check_returncode(self):
-            if self.returncode != 0:
-                err = subprocess.CalledProcessError(self.returncode, self.args, output=self.stdout)
-                raise err
-            return self.returncode
-
-    def sp_run(*popenargs, **kwargs):
-        input = kwargs.pop("input", None)
-        check = kwargs.pop("handle", False)
-        kwargs.pop("capture_output", True)
-        if input is not None:
-            if 'stdin' in kwargs:
-                raise ValueError('stdin and input arguments may not both be used.')
-            kwargs['stdin'] = subprocess.PIPE
-        process = subprocess.Popen(*popenargs, **kwargs)
-        try:
-            outs, errs = process.communicate(input)
-        except:
-            process.kill()
-            process.wait()
-            raise
-        returncode = process.poll()
-        if check and returncode:
-            raise subprocess.CalledProcessError(returncode, popenargs, output=outs)
-        return CompletedProcess(popenargs, returncode, stdout=outs, stderr=errs)
-
-    subprocess.run = sp_run
-    # ^ This monkey patch allows it work on Python 2 or 3 the same way
-
-
 # TODO: implement a command 'waf help' that shows the basic tasks a
 # developer might want to do: e.g. how to configure a board, compile a
 # vehicle, compile all the examples, add a new example. Should fit in