[ci] Kill hanged docker build process to avoid build timeout issue. (sonic-net#13726)

Why I did it
Docker build has a low rate of hanging up.
It hangs on different steps. So, it looks like a bug in docker daemon.

How I did it
Start a daemon process to scan running time more than 1 hours, and kill the process.

How to verify it

Author: liushilongbuaa

.azure-pipelines/azure-pipelines-build.yml

@@ -109,6 +109,7 @@ jobs:
 
     buildSteps:
       - template: template-skipvstest.yml
+      - template: template-daemon.yml
       - bash: |
           set -ex
           if [ $(GROUP_NAME) == vs ]; then

.azure-pipelines/cleanup.yml

@@ -1,5 +1,11 @@
 steps:
 - script: |
+    set -x
+    # kill daemon process
+    ps $(cat /tmp/azp_daemon_kill_docker_pid)
+    sudo kill $(cat /tmp/azp_daemon_kill_docker_pid)
+    rm /tmp/azp_daemon_kill_docker_pid
+
     if sudo [ -f /var/run/march/docker.pid ] ; then
         pid=`sudo cat /var/run/march/docker.pid` ; sudo kill $pid
     fi
@@ -11,4 +17,5 @@ steps:
         pid=`sudo cat dockerfs/var/run/docker.pid` ; sudo kill $pid
     fi
     sudo rm -rf $(ls -A1)
+  condition: always()
   displayName: "Clean Workspace"

.azure-pipelines/template-daemon.yml

@@ -0,0 +1,24 @@
+steps:
+- bash: |
+    (
+      while true
+      do
+        sleep 120
+        now=$(date +%s)
+        pids=$(ps -C docker -o pid,etime,args | grep "docker build" | cut -d" " -f1)
+        for pid in $pids
+        do
+          start=$(date --date="$(ls -dl /proc/$pid --time-style full-iso | awk '{print$6,$7}')" +%s)
+          time_s=$(($now-$start))
+          if [[ $time_s -gt $(DOCKER_BUILD_TIMEOUT) ]]; then
+            echo =========== $(date +%F%T) $time_s &>> target/daemon.log
+            ps $pid &>> target/daemon.log
+            sudo kill $pid
+          fi
+        done
+      done
+    ) &
+    daemon_pid=$!
+    ps $daemon_pid
+    echo $daemon_pid >> /tmp/azp_daemon_kill_docker_pid
+  displayName: start daemon to kill hang docker

.azure-pipelines/template-variables.yml

@@ -4,3 +4,5 @@ variables:
   SONIC_SLAVE_DOCKER_DRIVER: 'overlay2'
   SONIC_BUILD_RETRY_COUNT: 3
   SONIC_BUILD_RETRY_INTERVAL: 600
+  DOCKER_BUILDKIT: 0
+  DOCKER_BUILD_TIMEOUT: 3600