Remove Jitsu initialisation

What does this MR do and why?

This MR is part one of removing InitializeAnalyticsWorker which uses Jitsu. I've used GitLab Sidekiq guidelines to prepare this MR.

In the next minor release we'll delete the worker class.

Screenshots or screen recordings

How to set up and validate locally

1. In rails console disable the product_analytics_snowplow_support flag

   Feature.disable(:product_analytics_snowplow_support)

2. Visit graphql explorer http://gdk.test:3000/-/graphql-explorer
3. Run the following query

mutation {
  projectInitializeProductAnalytics(input: { projectPath: "flightjs/Flight" }) {
    project {
      fullPath
    }
    errors
  }
}

You should not get a success response

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #406659 (closed)