Invoke session middleware correctly.
Review Request #11977 — Created Jan. 22, 2022 and submitted
For a while, middleware was allowed to be invoked in the old way
(instantiate with no arguments and then call
process_request). This is
going away, and we'll need to instantiate with a
and go through the new-style chain. This change updates our tests which
manually invoke middleware to do that.
Ran unit tests.