ci: Rename the deqp/piglit-drivername-*.txt files to drivername-*.txt
We have two testsuites with the same format for fails/flakes/skips files, and test names that are definitely unique. As I'm about to add a third testsuite (gtest for libva-utils), so let's have just one file each for fails/flakes/skips instead of one per type of testsuite.