runtime: make improvements to global_queue_interval

[mox692]

Motivation

Resolve #5713. Currently specifying 0 or 1 for global_queue_interval causes a panic.

Solution

This PR:

• Added documentation indicating that setting global_queue_interval to 0 is not allowed and included an assert in the builder.
• Removed the debug_assert!(next > 1) that could be triggered when global_queue_interval is set to 1.
  • Although it's still unclear whether there is a practical benefit to always prioritize checking the global queue first, but i guess it's probably better than causing a panic in debug builds.