Common: make executor retry sleep interruptible by context cancellation

What does this MR do?

Makes executor retry delay interruptible by context cancellation instead of always waiting the full retry interval.

Why was this MR needed?

Currently retryCreateExecutor uses time.Sleep which ignores context cancellation. This can delay job cancellation responsiveness and keep the runner waiting unnecessarily. Using a context-aware wait allows faster shutdown and better resource responsiveness.

What's the best way to test this MR?

Run existing tests:

go test ./common

Behavior remains unchanged except retries now stop immediately if context is cancelled.

What are the relevant issue numbers?

None.