Disable the ec2-config test

"amazon-init.nix" is not included in the default AMIs because it
unconditionally runs a nixos-rebuild. Also, the test has never worked
(http://hydra.nixos.org/job/nixos/trunk-combined/nixos.tests.ec2-config).

Changed files
+1 -1
nixos
+1 -1
nixos/release.nix
···
tests.dockerRegistry = hydraJob (import tests/docker-registry.nix { system = "x86_64-linux"; });
tests.etcd = hydraJob (import tests/etcd.nix { system = "x86_64-linux"; });
tests.ec2-nixops = hydraJob (import tests/ec2.nix { system = "x86_64-linux"; }).boot-ec2-nixops;
-
tests.ec2-config = hydraJob (import tests/ec2.nix { system = "x86_64-linux"; }).boot-ec2-config;
+
#tests.ec2-config = hydraJob (import tests/ec2.nix { system = "x86_64-linux"; }).boot-ec2-config;
tests.firefox = callTest tests/firefox.nix {};
tests.firewall = callTest tests/firewall.nix {};
tests.fleet = hydraJob (import tests/fleet.nix { system = "x86_64-linux"; });