Fix: multi-vendor VXLAN tests must use low VNI values

Aruba CX developers can't grasp the concept of 24-bit VNI and use
only the low 16 bits. VNI values above 65535 work, but not with
other vendors who can use more than 16 fingers.

tests/integration/vxlan/08-vxlan-alt-vtep.yml

@@ -25,11 +25,13 @@ vlans:
     prefix:
       ipv4: 172.31.1.0/24
     links: [ s1-h1, s2-h2, s3-h3 ]
+    vni: 5000
   blue:
     mode: bridge
     prefix:
       ipv4: 172.31.1.0/24
     links: [ s1-h4, s2-h5 ]
+    vni: 5001
 
 nodes:
   s3:
@@ -55,13 +57,13 @@ links:
 
 validate:
   ping_red:
-    description: Ping-based reachability test in VLAN red (wait up to 30 seconds)
+    description: Ping-based reachability test in VLAN red
     wait_msg: Waiting for OSFP and STP to wake up
     wait: 50
     nodes: [ h1, h2 ]
     plugin: ping('h3')
   ping_blue:
-    description: Ping-based reachability test in VLAN blue (wait up to 10 seconds)
+    description: Ping-based reachability test in VLAN blue
     wait_msg: We might have to wait a bit longer
     wait: 10
     nodes: [ h4 ]