Revert "remove container"

This reverts commit d4ac952.

Author: boomanaiden154

.github/workflows/premerge.yaml

@@ -16,6 +16,11 @@ jobs:
     concurrency:
       group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
       cancel-in-progress: true
+    container:
+      image: ghcr.io/llvm/ci-ubuntu-22.04:latest
+    defaults:
+      run:
+        shell: bash
     steps:
       - name: Checkout LLVM
         uses: actions/checkout@v4