Minor tweak to packaging tests.

When an option is changed on a command object, calling ensure_finalized
for a second time will not run finalize_options again, because
ensure_finalized is a no-op the second time.  By resetting the finalized
attribute, we can be sure that whatever computation takes place in
finalize_options will happen again.

(In test_command_clean, I removed two lines that were a no-op.)

Lib/packaging/tests/test_command_clean.py

@@ -36,8 +36,6 @@ class cleanTestCase(support.TempdirManager, support.LoggingCatcher,
                              '%r was not removed' % path)
 
         # let's run the command again (should spit warnings but succeed)
-        cmd.all = True
-        cmd.ensure_finalized()
         cmd.run()