openshift tests ignored when run-test is a dangling symlink

[pkubatrh]

We should not only test whether the file exists but also if it is a symlink in case it fails the -e test.

https://github.com/sclorg/container-common-scripts/blob/master/test.sh#L23

[pkubatrh]

Possibly the same for run-conu in case we ever use it.

[phracek]

This is solved as separate test.

Feel free to re-open it in case it is still valid.