Add `seccompProfile` to Helm Chart

[lucacome]

When running in OpenShift we have the following warning

Warning: would violate PodSecurity "restricted:v1.24": allowPrivilegeEscalation != false (container "nginx" must set securityContext.allowPrivilegeEscalation=false), unrestricted capabilities (container "nginx-gateway" must not include "KILL" in securityContext.capabilities.add), seccompProfile (pod or containers "nginx-gateway", "nginx" must set securityContext.seccompProfile.type to "RuntimeDefault" or "Localhost")

this can be fixed (in part) by specifying

seccompProfile:
  type: RuntimeDefault

which is already the default if not specified.