Empty check 4 for ocp-3.9 should be removed 

Running `./docker-bench --version ocp-3.9` we see
 
```
[WARN] 4.10 Ensure secrets are not stored in Dockerfiles (Not Scored)
[WARN] 4.11 Ensure verified packages are only Installed (Not Scored)
[FAIL] 4.
[INFO] 5 Container Runtime
[WARN] 5.2 Ensure SELinux security options are set, if applicable (Scored)
```
Test 4 is empty and should be removed altogether. 