Fix a potential timeout in `Gitlab::Logger.read_latest`
If this method was called for a file that didn't exist, we attempted to
build it. But if the file wasn't writeable, such as a symlink
pointing to an unmounted filesystem, the method would just hang and
Further, this was entirely pointless since we were creating a file and
then shelling out to
tail, eventually returning an empty Array. Now we
just skip building it and return the empty Array straight away.
We should be defining the list of loggers in the controller, not the view.