Use in dict rather than "in dict.keys()". Fix linting warnings about "not in". (#8298)

* Fixed a few linting warnings for if not x in y.

These should have been caught by pylint, but weren't.

* Replaced "x in y.keys()" with "x in y".

It's much faster, and more Pythonic.

certbot-compatibility-test/certbot_compatibility_test/configurators/apache/common.py

@@ -57,7 +57,7 @@ class Proxy(configurators_common.Proxy):
 
     def _prepare_configurator(self):
         """Prepares the Apache plugin for testing"""
-        for k in entrypoint.ENTRYPOINT.OS_DEFAULTS.keys():
+        for k in entrypoint.ENTRYPOINT.OS_DEFAULTS:
             setattr(self.le_config, "apache_" + k,
                     entrypoint.ENTRYPOINT.OS_DEFAULTS[k])