ci: no strategy context in the composite action (vmpkg cache key per run)

.github/actions/vm-runner/action.yml

@@ -24,7 +24,7 @@ runs:
       uses: actions/cache@v4
       with:
         path: /mnt/work/vms/pkg-cache
-        key: vmpkg-${{ github.run_id }}-${{ github.job }}-${{ strategy.job-index }}
+        key: vmpkg-${{ github.run_id }}
         restore-keys: vmpkg-
     - name: Cache - the ISO (from the iso job)
       uses: actions/cache/restore@v4

.github/workflows/vmtest.yml

@@ -49,8 +49,6 @@ jobs:
         with:
           path: /mnt/work/iso
           key: steamify-iso-${{ steps.find.outputs.tag }}
-        env:
-          ISO_DIR: /mnt/work/iso
       - name: Download the ISO (once for every job)
         if: steps.cache.outputs.cache-hit != 'true'
         run: |