Pipeline template validate endpoint should show the extended configs for a job template

[VonnyJap]

What happened:

The pipeline template validation endpoint is displaying only the configurations stored in the database without extending the job template. Please refer to the details below.

What you expected to happen:

For the main job, the step following the extension of the job template should be the one displayed in the validator screenshot below.

How to reproduce it:

Take an example of pipeline template here and put into validator.