perf(ci): run CI-tooling tests once, not on every matrix leg

tests/scripts and tests/ci exercise bossbot scripts and workflow
guards — pure CI tooling. They were running on all unit matrix legs
(3 Pythons x 2 backends x 3 OSes). Move them to a single
test-ci-tooling run inside the Static Checks job.

Signed-off-by: phernandez <paul@basicmachines.co>

.github/workflows/test.yml

@@ -54,6 +54,10 @@ jobs:
         run: |
           just typecheck
 
+      - name: Run CI tooling tests
+        run: |
+          just test-ci-tooling
+
       - name: Run linting
         run: |
           just lint