[glean][arm][oss][gh] Use an arm image when using arm runners

Otherwise we would fail trying to set up docker on a bare arm linux
runner.

Notes:
- this runs directly on the provided runner (not a docker image, nesting)
- passwordless sudo

.github/workflows/ci-aarch64.yml

@@ -1,6 +1,6 @@
 # https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-syntax-for-github-actions
 name: CI-ARM
-on: [push]
+on: [push, pull_request]
 
 env:
   LANG: en_US.UTF-8
@@ -13,23 +13,22 @@ jobs:
       matrix:
         ghc: [8.10.7]
         compiler: [clang]
+
     runs-on: 4-core-ubuntu-arm
-    container:
-      image: ubuntu:22.04
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
 
       - name: Initialize APT
         run: |
-          apt-get update
-          apt-get install -y curl
+          sudo apt-get update
+          sudo apt-get install -y curl
 
       - name: Setup en_US.UTF-8 locale
         run: |
-          apt-get install -y locales
-          locale-gen en_US.UTF-8
-          update-locale LANG=en_US.UTF-8
+          sudo apt-get install -y locales
+          sudo locale-gen en_US.UTF-8
+          sudo update-locale LANG=en_US.UTF-8
 
       - name: Setup LOCAL_BIN environment
         run: |
@@ -41,29 +40,18 @@ jobs:
           echo "MAKEFLAGS=-j$(nproc)" >> "$GITHUB_ENV"
           echo "EXTRA_GHC_OPTS=-j$(nproc) +RTS -A128m -n2m -RTS" >> "$GITHUB_ENV"
 
-      - name: Setup Node
-        uses: actions/setup-node@v4
-        with:
-          node-version: 20
-
-      - name: Install indexer (flow)
-        run: npm install -g flow-bin
-
-      - name: Install indexer (typescript)
-        run: npm install -g @sourcegraph/scip-typescript
-
       - name: Setup Haskell
         run: |
           curl --proto '=https' --tlsv1.2 -sSf "https://downloads.haskell.org/~ghcup/aarch64-linux-ghcup" -o "$LOCAL_BIN"/ghcup
           chmod +x "$LOCAL_BIN"/ghcup
           ghcup install cabal --set
-          apt-get install -y build-essential libgmp-dev libnuma-dev
+          sudo apt-get install -y build-essential libgmp-dev libnuma-dev
           ghcup install ghc ${{ matrix.ghc }} --set
           echo "$HOME/.ghcup/bin" >> "$GITHUB_PATH"
 
       # This needs to be before the Clang step since they install GCC. We want to remove GCC if Clang is enabled.
       - name: Install CMake and Boost
-        run : apt-get install -y cmake libboost-all-dev
+        run : sudo apt-get install -y cmake libboost-all-dev
 
       - name: Setup Clang
         run: |