Fix: DO-3494: Make Table schema cache_key a query param

[Roman-Kornev]

Motivation and Context

The param was being sent as a body which is not allowed for a GET request.

Implementation Description

Any new dependencies Introduced

How Has This Been Tested?

PR Checklist:

• [x] I have implemented all requirements? (see JIRA, project documentation).
• [x] I am not affecting someone else's work, If I am, they are included as a reviewer.
• [x] I have added relevant tests (unit, integration or regression).
• [x] I have added comments to all the bits that are hard to follow.
• [x] I have added/updated Documentation.
• [x] I have updated the appropriate changelog with a line for my changes.

Screenshots (if appropriate):