OLM - Set default CatalogSource pod SecurityContext as `restricted`

With the introduction of the Pod Security Adminssion, the recommended best practice is to enforce the `restricted` policy of admission.

However, if the user creates the CatalogSource in the namespace running with `restricted` policy, the CatalogSource Pod fails to be created.

This is because when the `.spec.grpcPodConfig.securityContextConfig` is NOT SET in the CatalogSource, OLM treats the value's default as "legacy", which means that the Catalog Pod does NOT set the `restricted` securityContext, meaning that a Catalog pod will fail to run.

4.15

100%

1. On a OCP 4.15 cluster, create a custom CatalogSource object without `.spec.grpcPodConfig.securityContextConfig` being specified

2. See if the CatalogSource Pod started successfully without errors.

1. the CatalogSource Pod fails to be created with the error like:

status:
  message: >-
    couldn't ensure registry server - error ensuring pod: : error creating new
    pod: foobar-: pods "foobar-6ttkb" is forbidden:
    violates PodSecurity "restricted:v1.24": allowPrivilegeEscalation != false
    (container "registry-server" must set
    securityContext.allowPrivilegeEscalation=false), unrestricted capabilities
    (container "registry-server" must set
    securityContext.capabilities.drop=["ALL"]), runAsNonRoot != true (pod or
    container "registry-server" must set securityContext.runAsNonRoot=true),
    seccompProfile (pod or container "registry-server" must set
    securityContext.seccompProfile.type to "RuntimeDefault" or "Localhost")
  reason: RegistryServerError

The CatalogSource Pod started successfully by default without specifying `.spec.grpcPodConfig.securityContextConfig` as `restricted`