Add barebones E2E test for picklists

Testing the drag-and-rearrange functionality is proving harder than
expected, so we'll leave that for a later date. But this test at least
verifies that items can be added to and removed from picklists.
Speed up tests by 20 seconds

Now that we set up our E2E tests with a known environment (with only one
project in it), selecting the "100 projects per page" option is entirely
unnecessary, as it's already guaranteed that all projects in our test
environment will be on the first page of the projects list. By removing
the call to select100ItemsPerPage(), we can reduce the time to run all
E2E tests from about 7:30 to about 7:10, saving roughly twenty seconds.