Before this change, if a user requested a node to be cleaned
or "managed" with cleaning enabled when the user is in the
system scope, Ironic would attempt to user's token to
make the request to Neutron.
This, unfortunately, does not work, as the neutron client explicitly
requires a project ID to make the request to Neutron. As a result,
Ironic now falls back to it's internal credential configuration to make
the forward request, which matches the behavior if a node has been
unprovisioned and the cleaning has been started automatically.
Closes-Bug: 2048416
Change-Id: Id91ec6afcf89642fb3069918e768016b8b657a31
c3074524da