CI: Add instance console log to test-core-openstack.sh

Sometimes ping & ssh to the instance are failing - outputting instance console
log can help in the case when there are metadata access issues (or other
issues).

Change-Id: I8437300d621448782e964d877b2614ca606f5849

tests/test-core-openstack.sh

@@ -82,6 +82,8 @@ function test_instance_boot {
             break
         elif [[ $i -eq ${attempts} ]]; then
             echo "Failed to access server via SSH after ${attempts} attempts"
+            echo "Console log:"
+            openstack console log show kolla_boot_test
             return 1
         else
             echo "Cannot access server - retrying"