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
1 file changed