Closes: https://github.com/neondatabase/cloud/issues/17784
## Problem
Currently, we run the whole CI pipeline for any changes. It's slow and
expensive.
## Suggestion
Starting with MacOs builds:
- check what files were changed
- rebuild only needed parts
- reuse results from previous builds when available
- run builds in parallel when possible
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Co-authored-by: Alexander Bayandin <alexander@neon.tech>
