Ensure audit log permissions are restricted
Ensure audit log permissions are restricted

While the apiserver audit options merely use the lumberjack logger in
order to write the appropriate log files, this library has very loose
permissions by default for these files [1]. However, this library will
respect the permissions that the file has, if it exists already. This is
also the most tested scenario in the library [2].

So, let's follow the pattern marked in the library's tests and
pre-create the audit log file with an appropriate mode.

[1] https://github.com/natefinch/lumberjack/blob/v2.0/lumberjack.go#L280
[2] https://github.com/natefinch/lumberjack/blob/v2.0/linux_test.go

Signed-off-by: Juan Antonio Osorio Robles <jaosorior@redhat.com>

Kubernetes-commit: 42df7bc5b3aa26bf545b6392b557833c7162c472

kubernetes/apiserver,kubernetes/apiserver