Improve readability of MagicMock use in RYU test

Replaces an unnecessarily complex setup of a magicmock
in an RYU test module.

Change-Id: If2e99ff76114d896a6480a884a531f901198caa5
BSN: Set hash header to empty instead of False

Sets the consistency hash header to empty instead
of False since 'False' is handled like a string on
the backend and requires special-casing to detect.

Closes-Bug: #1325771
Change-Id: Iee1651574c01a32e78167a9bbed4e0433abbdec2
Merge "Improve readability of MagicMock use in RYU test"
Merge "BSN: Set hash header to empty instead of False"