middleware: remove oslo.context usage
middleware: remove oslo.context usage

There's nothing interesting in the fake context we're passing. Let's
stop depending on oslo.context all together here.

Change-Id: I7784bc3b818e67118e03905857c39eac66765fad

dims/oslo.messaging,dukhlov/oslo.messaging,apporc/oslo.messaging,apporc/oslo.messaging,ozamiatin/oslo.messaging,dukhlov/oslo.messaging,ozamiatin/oslo.messaging,dims/oslo.messaging