vlan: decreased num. of vlans created in not x86_64 machines
- decreased the number of vlans created in @vlan_create_500_vlans test to 200 for other archs (aarch64, s390x...)
- removed @vlan_create_many_vlans test, since its basically covered by @vlan_create_500_vlans
- renamed @vlan_create_500_vlans to @vlan_create_many_vlans, since it fits better now (since the number of vlans created is not always 500)