ubuntu_qrt_apparmor test will hang on azure nodes

The ubuntu_qrt_apparmor test will hang on the following azure testing nodes:
 * DS11_v2_promo
 * DS4
 * D4s_v3
 * E4s_v3
 * GS2
 * GS4-4
 * GS5-8
 * L8s
 * DS14_v2_promo
 * DS13_v2
 * B1s
 * D32s_v3
 * E4s
 * E32-8s
 * E64-16s

This is reproducible on every cycle, so I think this is not a regression.

From the job execution itself, it looks like the test was finished.
the "test_regression_testsuite" timed out and got terminated, log here:
https://pastebin.ubuntu.com/p/dSNprxDwdJ/

But it will stay in this state until the tester cancels the job, checking on the node you will see a zombie process:
  $ ps aux | grep Z
  USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
  azure 2984 0.0 0.0 0 0 ? Z Apr10 0:00 [sh] <defunct>

  $ pstree -p -s 2984
  systemd(1)───sshd(1247)───sshd(2559)───sshd(2634)───python3(2635)───sh(2984)

  $ ps aux | grep 2635
  azure 2635 0.0 0.0 124748 14188 ? Ssl Apr10 0:00 python3 ckct/runner --cloud azure ubuntu_qrt_apparmor

dmesg: http://paste.ubuntu.com/p/Qdx8KThG9W/

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-1004-azure 4.15.0-1004.4
ProcVersionSignature: User Name 4.15.0-1004.4-username 4.15.15
Uname: Linux 4.15.0-1004-azure x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
Date: Wed Apr 11 11:34:24 2018
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: linux-azure
UpgradeStatus: No upgrade log present (probably fresh install)