github: ignore cleanup failure, run only on self-hosted

.github/workflows/c-cpp.yml

@@ -1,6 +1,11 @@
 name: Build & Deploy Engine
 on: [push, pull_request]
 jobs:
+  cleanup:
+    runs-on: self-hosted
+    steps:
+    - name: Cleanup
+      run: rm -rf .* || true
   build:
     runs-on: ${{ matrix.os }}
     continue-on-error: true
@@ -42,8 +47,6 @@ jobs:
       ANDROID_SDK_TOOLS_VER: 4333796
       UPLOADTOOL_ISPRERELEASE: true
     steps:
-    - name: Cleanup
-      run: rm -rf .*
     - name: Checkout
       uses: actions/checkout@v2
       with: