[CLI Improvements] Migrate Tests to resource manager architecture - Backend - GET /tests/{id}

[xoscar]

As part of the changes to integrate the test resource manager created as part of this ticket

• [CLI Improvements] Migrate Tests to resource manager architecture - Backend - Test Manager#2607

We want to update the get single test endpoint to be removed from the open API scaffolding to use the resource manager structure instead.

Acceptance criteria

AC1
As a user working on the backend app
The GET /tests/{id} request should be wired up to the test manager
Using the structs and types from the new implementation

AC2
As a user working on the backend app
The changes done to use the new structure should not affect the database structure or data
To keep retro compability with the open API version

AC3
As a user working on the backend app
The rest of the scope outside of the get /tests/{id} request endpoint should not be touched