zuul: Increase GLANCE_LIMIT_IMAGE_SIZE_TOTAL for nova-lvm

As seen before in bug #1913451 the nova-lvm job creates large RAW
snapshots during each run due to the nature of using LVM storage for the
ephemeral instance disks.

Id425aa546f1a5973bae8be9c017782d18f0b4a47 recently landed capping the
per teneant image size total to 1000 MiB that is far too low for this
job given the RAW snapshots it's creating. This in turn resulted in
504 failures when n-cpu attempted to upload snapshots to g-api.

This change simply increases the per tenant limit to 10 GiB that should
be more than enough for all of the tests covered by the nova-lvm job.

Closes-Bug: #1938765
Change-Id: I824655387a10ac9b813c1b7b2399e25ed95f7fc3

Author: lyarwood

.zuul.yaml

@@ -189,6 +189,8 @@
         # snapshots from the LV based instance disks.
         # See bug #1913451 for more details.
         SWIFT_LOOPBACK_DISK_SIZE: 24G
+        # As above, increase the total image limit per tenant to 10G
+        GLANCE_LIMIT_IMAGE_SIZE_TOTAL: 10240
       devstack_services:
         # Disable non-essential services that we don't need for this job.
         c-bak: false