Disable glance secure hash in ceph job

Reference: https://review.opendev.org/c/openstack/glance_store/+/949383

This presumably affects any job based on
devstack-plugin-ceph-tempest-py3, but making the change here
for now.

Change-Id: Icb81924809da6ac7d375d8543b25c9bff160b615

.zuul.yaml

@@ -205,6 +205,10 @@
         # to turn this on (currently defaults to false):
         # MYSQL_REDUCE_MEMORY: true
       devstack_local_conf:
+        post-config:
+          $GLANCE_API_CONF:
+            DEFAULT:
+              do_secure_hash: False
         test-config:
           $TEMPEST_CONFIG:
             volume-feature-enabled: