Removes unnecessary Embrane module-level mocks

The embrane unit tests install a magicmock into
the system modules at the module level which
persists across all unit tests and isn't required.
This patch removes the unnecessary and limits the
life of the module mocks where they are necessary.

Partial-Bug: #1316401
Change-Id: Iaa38ee0c6821d46a6d78eefef39006df2c1c47e5
Merge "Removes unnecessary Embrane module-level mocks"