Split collaborations selenium specs into 2 files

Refs CNVS-15688

One file for the form specific specs, one file for the remainder.

Also deleted an unused method.

Test Plan:
Verify that both files run in under two minutes each, on Jenkins.

Change-Id: I0977a64a1bf85c411a1b7b9893755d889e015fc4
Reviewed-on: https://gerrit.instructure.com/41589
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brad Horrocks <bhorrocks@instructure.com>
Product-Review: Matthew Wheeler <mwheeler@instructure.com>
QA-Review: Matthew Wheeler <mwheeler@instructure.com>