[JIT Variant]: Reduce iterator stack on base signals

[dshemetov]

This is a variant of #1026.

Prerequisites:

• Unless it is a documentation hotfix it should be merged against the dev branch
• Branch is up-to-date with the branch to be merged with, i.e. dev
• Build is successful
• Code is cleaned up and formatted

Summary

Create an early exit from the JIT iterator stack for non-derived signals. The advantage of this approach is that it still relies on a single database query, instead of making multiple, like #1026.