Add project_namespace_ids in zoekt_indices metadata

What does this MR do and why?

We have db timedout issue for namespace.all_projects. gitlab-com/gl-infra/production#19157 (comment 2320139002)

Our plan is to iterate over ProjectNamespace to fix this. Since we will iterate over project_namespaces in batch we need to set project_namespace_id_from and project_namespace_id_to in the metadata because it will be sorted by project_namespace.id. So this MR will add project_namespace_id_from and project_namespace_id_to in the metadata.

Since we will run the rollout script manually, we can make sure that there are no zoekt_indices in the pending state before running the script. So, I think it is safe to remove the project_id_to and project_id_to checks in the InitialIndexingEventWorker.

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Related to #515808 (closed)