Set nodepool swap size back to 8GB

A recent patch lowered the swap space available on nodepool
instance from 8GB to 1GB. This is causing nova to not have enough
memory to boot VMs required for some tests.
This patch restores the 8GB swap value for these jobs.

[1] https://review.opendev.org/#/c/750941/

Change-Id: I19c3465fb39a6204a5a167ac75b6eed832f9fe72

zuul.d/jobs.yaml

@@ -182,6 +182,7 @@
     required-projects:
       - openstack/diskimage-builder
     vars:
+      configure_swap_size: 8192
       devstack_localrc:
         DIB_LOCAL_ELEMENTS: openstack-ci-mirrors
         LIBVIRT_TYPE: kvm
@@ -219,6 +220,7 @@
     required-projects:
       - openstack/diskimage-builder
     vars:
+      configure_swap_size: 8192
       devstack_localrc:
         DIB_LOCAL_ELEMENTS: openstack-ci-mirrors
       devstack_local_conf:
@@ -253,6 +255,7 @@
       - openstack/diskimage-builder
     host-vars:
       controller:
+        configure_swap_size: 8192
         devstack_localrc:
           # From devstack "vars:"
           DATABASE_USER: octavia
@@ -294,6 +297,7 @@
           '/var/log/octavia-amphora.log': logs
           '/var/log/octavia-tenant-traffic.log': logs
       controller2:
+        configure_swap_size: 8192
         devstack_localrc:
           # From devstack "vars:"
           DATABASE_USER: octavia