fix(build-system-tests): bound Android emulator boot-wait to stop 6h canary hangs (#7031)

The macos-15-intel React Native Android canary regularly cold-boots into a
wedged emulator. With no job timeout and an unbounded `adb wait-for-device`
boot-wait loop, the job spins until GitHub's 6h hard limit cancels it.
Compounding this, the snapshot cache key always hits but the cached snapshot
is incompatible with the current runner emulator ("Failed to load snapshot
'default_boot'"), while the snapshot-resave step is gated on a cache miss, so
the broken snapshot stays sticky.

Minimum mitigation:
- timeout-minutes: 45 on the emulator job so a wedged boot can't burn 6h.
- Wrap the boot-wait in `timeout 420` in both the cold-boot and cached steps;
  on timeout, emit a ::error:: annotation, dump `adb devices`, and fail fast.
  This needs GNU coreutils on macOS (brew install coreutils), mirroring the
  proven recipe in reusable-e2e.yml.
- Bump the snapshot cache key v1 -> v2 so a compatible snapshot is regenerated
  on the next cold boot.

Follow-up (not in this PR): replace the hand-rolled emulator launch with
reactivecircus/android-emulator-runner and move the Android matrix to
ubuntu-latest (KVM) for reliability and speed.

Co-authored-by: soberm <12175134+soberm@users.noreply.github.com>

Author: soberm

.github/workflows/reusable-build-system-test-react-native.yml

@@ -11,6 +11,8 @@ on:
 jobs:
   build:
     runs-on: macos-15-intel
+    # Bound the whole job so a wedged emulator boot can't run until GitHub's 6h hard limit.
+    timeout-minutes: 45
     strategy:
       fail-fast: false
       matrix:
@@ -87,7 +89,7 @@ jobs:
             ~/Library/Android/sdk/build-tools
             ~/Library/Android/sdk/platform-tools
             ~/.android/avd
-          key: ${{ runner.os }}-android-sdk-27-x86_64-snapshot-v1
+          key: ${{ runner.os }}-android-sdk-27-x86_64-snapshot-v2
         env:
           SEGMENT_DOWNLOAD_TIMEOUT_MINS: 5
 
@@ -126,14 +128,20 @@ jobs:
         run: |
           echo -e "echo \$ANDROID_HOME"
           echo $ANDROID_HOME
+          # macOS runners have no GNU `timeout`; coreutils provides it for the emulator boot-wait guard below (mirrors reusable-e2e.yml).
+          brew install coreutils
           $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager --install "build-tools;33.0.2" "platform-tools" "system-images;android-27;default;x86_64"
           $ANDROID_HOME/cmdline-tools/latest/bin/avdmanager create avd --name Pixel_5_API_27 --force --device "pixel_5" --abi x86_64 --package "system-images;android-27;default;x86_64"
 
       - name: Start Android emulator (cold boot - first run)
         if: ${{ matrix.platform == 'android' && steps.android-cache.outputs.cache-hit != 'true' }}
         run: |
           $ANDROID_HOME/emulator/emulator -avd Pixel_5_API_27 -port ${{ env.EMULATOR_PORT }} -no-boot-anim -no-audio -no-snapshot-load -gpu host -accel on &
-          $ANDROID_HOME/platform-tools/adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed | tr -d '\r') ]]; do sleep 1; done; input keyevent 82'
+          if ! timeout 420 $ANDROID_HOME/platform-tools/adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed | tr -d '\r') ]]; do sleep 1; done; input keyevent 82'; then
+            echo "::error::Android emulator did not reach sys.boot_completed within 420s; failing fast instead of hanging until the 6h limit"
+            $ANDROID_HOME/platform-tools/adb devices
+            exit 1
+          fi
           $ANDROID_HOME/platform-tools/adb devices
           # disable spell checker
           $ANDROID_HOME/platform-tools/adb shell settings put secure spell_checker_enabled 0
@@ -148,7 +156,11 @@ jobs:
         if: ${{ matrix.platform == 'android' && steps.android-cache.outputs.cache-hit == 'true' }}
         run: |
           $ANDROID_HOME/emulator/emulator -avd Pixel_5_API_27 -port ${{ env.EMULATOR_PORT }} -no-boot-anim -no-audio -snapshot default_boot -gpu host -accel on &
-          $ANDROID_HOME/platform-tools/adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed | tr -d '\r') ]]; do sleep 1; done; input keyevent 82'
+          if ! timeout 420 $ANDROID_HOME/platform-tools/adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed | tr -d '\r') ]]; do sleep 1; done; input keyevent 82'; then
+            echo "::error::Android emulator did not reach sys.boot_completed within 420s; failing fast instead of hanging until the 6h limit"
+            $ANDROID_HOME/platform-tools/adb devices
+            exit 1
+          fi
           $ANDROID_HOME/platform-tools/adb devices
 
       - name: Create MegaApp ${{ env.MEGA_APP_NAME }} and run build on NodeJS ${{ matrix.node-version }}