Bug 1877348 - Remove the try/except wrappers that end up calling distutils.core.setup r=firefox-build-system-reviewers,glandium

This is one of the last references to `distutils` within `mach`, so
let's get rid of it to be thorough.

Differential Revision: https://phabricator.services.mozilla.com/D199951

python/mach/setup.py

@@ -4,11 +4,7 @@
 
 import os
 
-try:
-    from setuptools import setup
-except ImportError:
-    from distutils.core import setup
-
+from setuptools import setup
 
 VERSION = "1.0.0"
 HERE = os.path.dirname(__file__)

python/mozboot/setup.py

@@ -2,10 +2,7 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this file,
 # You can obtain one at http://mozilla.org/MPL/2.0/.
 
-try:
-    from setuptools import setup
-except ImportError:
-    from distutils.core import setup
+from setuptools import setup
 
 VERSION = "0.1"