runtime_test: skip virgl test on fedora 34

The gtk and headless tests fail on Fedora 34 because of the host libdrm
version so skip them.

| runqemu - ERROR - Failed to run qemu: MESA-LOADER: failed to open iris: /lib64/libdrm_nouveau.so.2: undefined symbol: drmCloseBufferHandle (search paths /usr/lib64/dri)
| failed to load driver: iris
| MESA-LOADER: failed to open kms_swrast: /lib64/libdrm_nouveau.so.2: undefined symbol: drmCloseBufferHandle (search paths /usr/lib64/dri)
| failed to load driver: kms_swrast
| MESA-LOADER: failed to open swrast: /lib64/libdrm_nouveau.so.2: undefined symbol: drmCloseBufferHandle (search paths /usr/lib64/dri)
| failed to load swrast driver
| qemu-system-x86_64: egl: gbm_create_device failed
| qemu-system-x86_64: egl: render node init failed

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>