typo in the r300 job stage and improve test jobs filter

!128 (merged) introduced the r300-* jobs in the amd-postmerge stage to be triggered by the tool on the testing and verification pipelines, but a typo in the stage name didn't allow it to do the task.

The filter is made after the discard of r".*(traces|fossils|skqp|deqp|angle).*" jobs, so from the current set of r300-* jobs (aka r300-rv380-deqp-gles2, r300-rv410-deqp-piglit, r300-rv530-deqp-gles2, r300-rv530-nine, r300-rv530-piglit), only the last two would be trigger. So, it is also required to improve this other filter to not discard jobs with deqp in the name if they have also piglit in the name.