ci/freedreno: Reduce concurrency when replaying traces on a630
We are running out of memory when replaying traces sometimes, reduce the number of concurrent retrace processes.
Mesa: User error: GL_OUT_OF_MEMORY in glReadPixels warning: GL_OUT_OF_MEMORY while getting snapshot 1074335: warning: failed to get snapshot
https://gitlab.freedesktop.org/mesa/mesa/-/jobs/20519522
Signed-off-by: Tomeu Vizoso tomeu.vizoso@collabora.com