[Feature flag] Enable namespace name sync with CustomersDot

Summary

This issue is to rollout this feature on production, that is currently behind the sync_namespace_name_with_cdot feature flag.

Context for the change

When the name for namespace changes in GitLab.com, no notice of the change is sent to CustomersDot.

As a result, the subscription information on CustomersDot gets out of sync and displays the outdated name within the customer's subscription page.

We want for the subscriptions in CustomersDot to display accurate information regarding its associated namespaces in Gitlab.com.

Owners

• Team: grouplicense
• Most appropriate slack channel to reach out to: #g_license
• Best individual to reach out to: Vladlena Shumilo (@vshumilo)
• PM: James Lopez (@jameslopez)

The Rollout Plan

• Rollout Feature for everyone as soon as Sidekiq is updated and the introduced job is available. More context

Expectations

What are we expecting to happen?

When the flag is enabled, every time a EE::Namespace object's name is updated, we will enqueue a ::Namespaces::SyncNamespaceNameWorker that will take care of sending the updated name to CustomersDot so it is properly updated on that end.

What might happen if this goes wrong?

The name will not be updated, we will be in the same situation we are today.

Roll Out Steps

• Enable on staging (/chatops run feature set sync_namespace_name_with_cdot true --staging)
• Test on staging
• Ensure that documentation has been updated
• Coordinate a time to enable the flag with the SRE oncall and release managers
  • In #production mention @sre-oncall and @release-managers. Once an SRE on call and Release Manager on call confirm, you can proceed with the rollout
• Announce on the issue an estimated time this will be enabled on GitLab.com
• Enable on GitLab.com by running chatops command in #production (/chatops run feature set sync_namespace_name_with_cdot true)
• Cross post chatops Slack command to #support_gitlab-com (more guidance when this is necessary in the dev docs) and in your team channel
• Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry. Ensure that the feature flag definition YAML file has been removed in the same MR that is removing the feature flag from the code
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel

Rollback Steps

• This feature can be disabled by running the following Chatops command:

/chatops run feature set sync_namespace_name_with_cdot false