Fix target KPI usage in tutorials

[ofirgo]

Pull Request Description:

We moved the target_kpi argument from the facades to the mixed precision config.
This PR fixes this in all tutorials and quick start.
In addition, we adding an option to set the target KPI after initializing the core config with the mp config inside it.

Checklist before requesting a review:

• I set the appropriate labels on the pull request.
• I have added/updated the release note draft (if necessary).
• I have updated the documentation to reflect my changes (if necessary).
• All function and files are well documented.
• All function and classes have type hints.
• There is a licenses in all file.
• The function and variable names are informative.
• I have checked for code duplications.
• I have added new unittest (if necessary).