add securitycontext

[andrewh1978]

No description provided.

[bplein]

Tested on Vanilla, got the following error:

  Type     Reason     Age               From               Message
  ----     ------     ----              ----               -------
  Normal   Scheduled  56s               default-scheduler  Successfully assigned chewram/chewram-c229j to node-1-1
  Normal   Pulled     1s (x6 over 55s)  kubelet            Container image "andrewh1978/px-bench" already present on machine
  Warning  Failed     1s (x6 over 55s)  kubelet            Error: container has runAsNonRoot and image will run as root (pod: "chewram-c229j_chewram(c710d424-d4cf-4ff9-854d-ec802da7be8c)", container: chewram)```

[bplein]

@andrewh1978 I removed the RunAsNonRoot and it works in vanilla. Can you retest chewram.yml in OCP?

I might also covert this to run in px-bench namespace, we don't need to litter in 2 of them.