Shuffle virtual IPs for VMs in runtest.py

This somewhat reduces risk of two simultaneously booted HA VMs
trying to get the same virtual IP as well as reducing the impact
of an AD test run failing to properly clean up after itself.

tests/runtest.py

@@ -9,6 +9,7 @@
 from sys import argv, exit
 import os
 import getopt
+import random
 import socket
 import sys
 import secrets
@@ -206,7 +207,12 @@ def get_ipinfo(ip_to_use):
     elif os.environ.get('virtual_ip'):
         vip = os.environ['virtual_ip']
     else:
-        for i in ip_interface(f'{ip}/{netmask}').network:
+        # reduce risk of trying to assign same VIP to two VMs
+        # starting at roughly the same time
+        vip_pool = list(ip_interface(f'{ip}/{netmask}').network)
+        random.shuffle(vip_pool)
+
+        for i in vip_pool:
             last_octet = int(i.compressed.split('.')[-1])
             if last_octet < 15 or last_octet >= 250:
                 # addresses like *.255, *.0 and any of them that