set-matrix: run on ubuntu-slim

GitHub now provides a lightweight runner [1], which is perfect for
little jobs like set-matrix.

[1] https://github.blog/changelog/2026-01-22-1-vcpu-linux-runner-now-generally-available-in-github-actions/

Signed-off-by: Ihor Solodrai <[email protected]>

Author: theihor

.github/workflows/test.yml

@@ -15,12 +15,7 @@ concurrency:
 
 jobs:
   set-matrix:
-    # FIXME: set-matrix is lightweight, run it on any self-hosted machines for kernel-patches org
-    # so we do not wait for GH hosted runners when there potentially all are busy because of bpf-rc
-    # repo for instance.
-    # This could be somehow fixed long term by making this action/workflow re-usable and letting the called
-    # specify what to run on.
-    runs-on: ${{ github.repository_owner == 'kernel-patches' && 'x86_64' || 'ubuntu-latest' }}
+    runs-on: ubuntu-slim
     permissions: read-all
     outputs:
       build-matrix: ${{ steps.set-matrix-impl.outputs.build_matrix }}