config.yaml: Removed the CEX UUID from config.yaml

IBM cloud does not have CEX hardware and CI test on
FCOS is not possible. Hence removing the device UUID from env.

config.yaml

@@ -23,12 +23,6 @@ streams:
 
 additional_arches: [aarch64, ppc64le, s390x]
 
-env:
-  # This matches the UUID in multi-arch-builders/create-cex-device.sh
-  # Ideally, we'd pass this a cleaner way. See also:
-  # https://github.com/coreos/coreos-assembler/pull/3828#discussion_r1669010741
-  KOLA_CEX_UUID: "68cd2d83-3eef-4e45-b22c-534f90b16cb9"
-
 source_config:
   url: https://github.com/coreos/fedora-coreos-config