Improvement: Query Insights should be cancellable at each stage

[tnaum-ms]

Currently Stage 1 + Stage 2 don't have a time limit and can't be easily cancelled.

This is risky in connection with a complex query.

Task:

• Introduce timeouts (e.g. 10-20-30 seconds)
• Support cancellation in the frontend (cancel UI) and in the backend (AbortSignal?)