insights: Add codeInsightsCriticalTelemetry into ping payload

Created by: CristinaBirkel

Closes https://github.com/sourcegraph/sourcegraph/issues/32745

Description

Our critical telemetry ping (total insights) wasn't getting published. I believe this fixes it!

Test plan

I tried to test this out locally. There may be a better way, but here's what I did. (The real test will be once it is deployed to k8s.)

1. Add some logging to cmd/frontend/internal/app/updatecheck/handler.go below this line:

fmt.Println("Message:")
var p pingPayload
var t types.CodeInsightsCriticalTelemetry
json.Unmarshal(message, &p)
json.Unmarshal(p.CodeInsightsCriticalTelemetry, &t)
fmt.Println(t)

That will allow you to see what is being published.

2. sg start dotcom
3. Then make a request POST https://sourcegraph.test:3443/.api/updates with a body (you may need to change the site number to your own?):

{
    "site":  "b300fe72-89bf-4927-b3a7-76c32396a98c",
    "version": "3.8.0",
    "CodeInsightsCriticalTelemetry": { "TotalInsights": 15 } 
}

4. Check your logs. Before this change, I was seeing a 0. After the change, I see a 15. So that gives me some confidence that this fix is correct.