Have Github actions reuse Makefile commands

[dusan-maksimovic]

Currently in the rust.yml workflow we have this:

cargo test --workspace --exclude test-e2e --verbose --no-fail-fast

And in Makefile we also have this:

test-unit: cargo test --workspace --exclude test-e2e --lib --no-fail-fast

We should rewrite the workflow file to reuse Makefile commands, so we don't need to maintain the same thing in two places.
This applies to all actions, not just unit tests.