rabbit/qpid: remove the args/kwargs from ensure()

Having an *args list following the retry kwargs just screams:

  SyntaxError: non-keyword arg after keyword arg

but we don't actually pass any args to methods invoked via ensure() so
these are just unused and can be removed. If we did want them in future
we could just use functools.partial().

Change-Id: Idef12bbc94d39c84ee06ddd6d743f3d2f705a8d1
Merge "rabbit/qpid: remove the args/kwargs from ensure()"