Remove the right file in revoke-sudo

Also fix the negative test to use shell instead of command, so that
! is parsed as intended.

Change-Id: I9f9dd60a895798cc639863a36b921b64621f6767

roles/revoke-sudo/README.rst

@@ -1,6 +1,6 @@
 Remove sudo access for the Zuul user.
 
-If the file ``/etc/sudoers.d/zuul-sudo`` exists, then it will be
+If the file ``/etc/sudoers.d/zuul`` exists, then it will be
 removed.  This is to facilitate systems which may use the same image
 for tests which require sudo and those which do not.
 

roles/revoke-sudo/tasks/main.yaml

@@ -1,8 +1,8 @@
 - name: Remove sudo access for zuul user.
   become: yes
   file:
-    path: /etc/sudoers.d/zuul-sudo
+    path: /etc/sudoers.d/zuul
     state: absent
 
 - name: Prove that general sudo access is actually revoked.
-  command: ! sudo -n true
+  shell: '! sudo -n true'