Remove default semantic model

• The default semantic model takes up unnecessary real estate in the Fabric workspace. If I don't want the default semantic model, I should be able to remove it.

• The default semantic model is confusing, because you cannot modify it through the default semantic model item, instead you need to look inside the SQL Analytics Endpoint to modify the default semantic model.

• The default semantic model doesn't support server timings and some other features in DAX studio. For this, you need to create a new custom semantic model.

• The default semantic model cannot be manually refreshed, so you cannot clear it's cache for performance testing. For this, you need to create a new custom semantic model.

Bottom line: the default semantic model is annoying and should be removed.