Continue disable the GLOBAL_VENV in grenade job

Grenade is moving to virtual env by default
- https://review.opendev.org/c/openstack/grenade/+/930507

and ironic job is failing on virtual env
- https://zuul.opendev.org/t/openstack/build/f5c4aa3dd64047a1909c4a964ad89aa8/log/controller/logs/grenade.sh_log.txt#15028

Until ironic greande job is ready for virtual env,
let's continue disable it in ironic side.

Change-Id: Ia76054c7b977dd17778dc4c89e8e212ab22f51af

zuul.d/ironic-jobs.yaml

@@ -1079,6 +1079,9 @@
           # Required as different access rights are used by default
           # and the classic devstack config which is defaulted doesn't work.
           IRONIC_ENFORCE_SCOPE: True
+          # By default Grenade works on virtual env but Ironic need more work
+          # to enable it. Once Ironic is ready we can remove the below setting. 
+          GLOBAL_VENV: false
         old:
           IRONIC_VM_LOG_DIR: '{{ devstack_bases.old }}/ironic-bm-logs'
       grenade_localrc:
@@ -1187,6 +1190,9 @@
           EBTABLES_RACE_FIX: True
           LIBVIRT_STORAGE_POOL_PATH: /opt/libvirt/images
           IRONIC_VM_LOG_DIR: '/opt/stack/ironic-bm-logs'
+          # By default Grenade works on virtual env but Ironic need more work
+          # to enable it. Once Ironic is ready we can remove the below setting.
+          GLOBAL_VENV: false
       grenade_localrc:
         BASE_RUN_SMOKE: False
       devstack_plugins: