resourceloader: Remove use of object registering in test suites

resourceloader: Remove use of object registering in test suites

This was done as a "clever" shortcut to make sure tests a little
but shorter, but also made them less consistent with normal code.

Remove this in favour of 'class' or 'factory' options as needed.
Also remove a bunch of unneeded register() calls.

The tests cover everything affected by this change.

Side fix - isFileModule should reject modules with 'factory'
the same way it rejected raw objects and non-FileModule 'class'
cases already. This is now covered by tests as well.

Bug: T222637
Change-Id: I3996317dbcd780cc6e0f82c84e769c08a3fc42bb