Get rid of old browsertest files

There is no CI running them regularely anymore.
As not all of them are migrated to new testfiles yet, we'll keep a copy of them in https://github.com/wmde/WikidataBrowserTestsRSpec

Bug: 66468
Change-Id: I598469976be25b83587f627e483d33f8f36c37ca
Merge "Get rid of old browsertest files"