Expect two epg tests to fail on hydra

* test/lisp/epg-tests.el (epg-decrypt-1, epg-roundtrip-1):
These currently fail for unknown reasons on hydra.nixos.org.
1 job for master in 3 seconds (queued for 2 seconds)
Status Job ID Name Coverage
failed #296


Name Stage Failure
test Test There has been a runner system failure, please try again
Running with gitlab-runner 11.4.2 (cf91d5e1)
on gitlab-runner-docker cff9d373
Using Docker executor with image debian:stretch ...
Pulling docker image debian:stretch ...
Using docker image sha256:4879790bd60d439cfe39c063660eef7af525d5f6f1cbb701a14c7cfc11cbfcf7 for debian:stretch ...
ERROR: Job failed (system failure): Error response from daemon: open /var/run/docker/libcontainerd/containerd/8f7ccc7a36f7850b09df8d4c2a781974dbeb01be59be6e0a42df935189e4e022/init/shim-log.json: no such file or directory (executor_docker.go:1015:1s)