Query Reporting: Identify new queries introduced during a merge request

After Query Reporting: Record auto_explain plans for ... (#414325 - closed), we will have a list of every unique query per in an rspec run. We can use this to identify the new queries introduced in an MR. In this issue, we produce the data required for that process.

• Diff the set of queries produced by Query Reporting: Record auto_explain plans for ... (#414325 - closed) against a known set from a run of the master pipeline
• Record this in a new artifact for further use.