Create gitlab-elasticsearch-indexer security mirror repository

Issue

During a recent discussion about a dependency update, it became apparent that the elasticsearch-indexer does not have a mirror repository in the security group. In the event that we need to apply a security fix, having that repository in place would allow us to review and iterate on a fix privately and without the additional delay of getting the security repository setup.

Solution

1. Have a security mirror repository created in the security group (@ankelly has asked the release team for assistance with this)
2. Follow the steps detailed in the Configuring Security Mirroring documentation. Doing this requires:

• Having the ability to access the 'Settings' section of the canonical gitlab-elasticsearch-indexer repository
• Having access to the Engineering 1Password vault