Is your feature request related to a problem? Please describe.

We currently have a metamorphic test at the KV layer, which runs nightly. With the addition of range keys (as part of the work for #70429), we'll want to enhance the metamorphic test harness to ensure that we have coverage of MVCC operations that make use of range keys.

This will no doubt prove invaluable in detecting edge-cases that would otherwise be very tricky to write tests for, or even dream up in the first place!

Describe the solution you'd like

Extend the existing MVCC metamorphic tests to cover operations that use Pebble range keys.

Jira issue: CRDB-16537

Epic CRDB-2624