[5.x] remove an unused test file (#11322)

[stacey-gammon]

It references files that don’t exist anymore, anyhow. Backports #11322

[stacey-gammon]

Second time I've run across this in 5.x:

        │ debg  in findAllByCssSelector: .filter-bar > .filter
           │ debg  Found 0 for selector .filter-bar > .filter
         └- ✖ fail: "dashboard app dashboard view edit mode shows lose changes warning and loses changes on confirmation when a filter is deleted"
         │        TypeError: Cannot read property 'click' of undefined
         │         at Context.<anonymous> (test/functional/apps/dashboard/_view_edit.js:181:17)
         │         at undefined.next (native)

filed: #11339
jenkins, test this

[stacey-gammon]

jenkins, test this