Add a flag to disable diagram searching

[m-mohamedin]

Is your feature request related to a problem? Please describe.
The search request sometimes cause a large DB load

Describe the solution you'd like
Add a flag to disable diagram searching

Additional context
DID-17143

Note: Disabling search will break recent and search in inserting a diagram splash screen. Also, embedding a diagram will be broken without the search

[davidjgraph]

Another option is to move recent diagrams to their own section on the left hand side.

We could move "from this page" into search with a "search only this page" tickbox. Then have search and recent as their own sections that don't cause a search by default.

The "blank" section is wrong anyway. "Blank" is the wrong title and clicking the diagram types doesn't open those libraries in the editor. Maybe "Quick start".