Limit concurrency of non-persistent tasks

[gajus]

There should be a way to ensure that we don't run all triggers at once.

This is particularly relevant for when Turbowatch starts.

At the moment, if we load all scripts, such as turbowatch **/turbowatch.ts this will immediately fire all triggers that are required to run at start. That produces high congestion of CPU/logs. We should provide a reasonable (configurable) default, such as 10.