Move tljh-config symlink to /usr/bin

Removes a lot of 'sudo -E' usage, and eventually should
let us get rid of the $PATH override for jupyterhub-admins,
which arguably is less secure than just dropping stuff into
/usr/bin

Also remove sudo -E from apt and mkdir calls. Not necessary.

integration-tests/test_install.py

@@ -209,4 +209,4 @@ def test_symlinks():
     """
     Test we symlink tljh-config to /usr/local/bin
     """
-    assert os.path.exists('/usr/local/bin/tljh-config')
+    assert os.path.exists('/usr/bin/tljh-config')