[github] Use ubuntu-slim runner

This commit changes runner for simple checker workflow to ubuntu-slim.

ONE-DCO-1.0-Signed-off-by: Hyeongseok Oh <hseok82.oh@samsung.com>

Author: hseok-oh

.github/workflows/check-format.yml

@@ -17,7 +17,7 @@ defaults:
 jobs:
   check-format:
     name: Check format
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-slim
     if: github.repository_owner == 'Samsung'
 
     steps:

.github/workflows/check-pr-commit.yml

@@ -18,7 +18,7 @@ defaults:
 jobs:
   check-commit-message:
     name: Check commit message
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-slim
     # Skip on draft, check on draft -> ready
     if: github.repository_owner == 'Samsung' && github.event.pull_request.draft == false