Refactor common tests out of projects testing

There were some duplicate tests in the last projects test as admin;
moved them into helper functions.
Projects admin test: Consolidate helper functions

We have two pairs of functions that differ only in the .toBeFalsy() or
.toBeTruthy() expectations. We can swap those for .toBe(bool) and
passing in the expected boolean value (because we know that the values
returned by .isDisplayed() will always be booleans, not other objects
whose truthiness or falsiness we need to test). This will make our code
slightly easier to read and have less duplication.

Also, this fixes the one test that the previous commit broke (it needed
access to one of the variables that was moved into the helper functions).