Move `securityContext` to container level

[rimusz]

Currently all charts securityContext have in deployment/statefulset spec level which breaks Istio proxy injection container work., moving securityContext to container level will sort the problem.

        securityContext:
          runAsUser: {{ .Values.xxx.uid }}
          fsGroup: {{ .Values.xxx.uid }}

[rimusz]

awesome!

[zendril]

@danielezer I don't see any context, why is this re-opened?

[danielezer]

@zendril I moved the securityContext to container level and it broke the permissions on the volumes so I reverted it. Now it is back to how it was before, which is at the pod level