cmd/pings: set up msp_delivery (#62109)

Sets up CD to pings rollout pipeline.

## Test plan

Rolled out sourcegraph/managed-services#1274 and did manual setup step:

```
$ gcloud deploy apply --project=pings-prod-2f4f73edf1db --region=us-central1 --file=rollout-us-central1.clouddeploy.yaml
Waiting for the operation on resource projects/pings-prod-2f4f73edf1db/locations/us-central1/targets/prod-us-central1...done.      
Created Cloud Deploy resource: projects/pings-prod-2f4f73edf1db/locations/us-central1/targets/prod-us-central1.
```

cmd/pings/BUILD.bazel

@@ -2,6 +2,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 load("//dev:oci_defs.bzl", "image_repository", "oci_image", "oci_push", "oci_tarball")
 load("@rules_pkg//:pkg.bzl", "pkg_tar")
 load("@container_structure_test//:defs.bzl", "container_structure_test")
+load("//dev:msp_delivery.bzl", "msp_delivery")
 
 go_library(
     name = "pings_lib",
@@ -60,3 +61,10 @@ oci_push(
     image = ":image",
     repository = image_repository("pings"),
 )
+
+msp_delivery(
+    name = "msp_deploy",
+    gcp_project = "pings-prod-2f4f73edf1db",
+    msp_service_id = "pings",
+    repository = "index.docker.io/sourcegraph/pings",
+)