Missing IPV6_AUTOCONF=no to render sysconfig dhcp6 stateful on RHEL

[otubo]

Proposed Commit Message

IPV6_AUTOCONF needs to be set to 'no' on RHEL so NetworkManager can
properly acquire ipv6 address.

rhbz: #1859695

Signed-off-by: Eduardo Otubo otubo@redhat.com

Additional Context

According to additional tests from the reporter Tom Barron on the Original Bugzilla (1859695) the option IPV6_AUTOCONF should also be set to no on this specific case. Most of the BZ is marked as private, though.

Test Steps

(as described on the above mentioned BZ)
Steps to Reproduce:

1. Create StorageNFS network with IPv6 CIDR and address range defined
2. Create a Nova instance with 2 NICs, 2nd NIC connected to StorageNFS network
3. Login to VM and examin Eth1 IP address

Actual results:
The Nova assigned IPv6 address was not assigned to device Eth1

Expected results:
Expected the Nova assigned IP address to be assigned to Eth1 interface

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Thanks!