Enable GLOBAL_VENV in ironic grenade jobs

grenade by default enable GLOBAL_VENV which means it
install and run everything from virtual env

- https://review.opendev.org/c/openstack/grenade/+/930507

We faced the error in ironic grenade scripts in virtual env
so GLOBAL_VENV was disabled explicitly. This fixing the scripts
and enable GLOBAL_VENV in ironic jobs also.

Change-Id: I48ee1dd4adc2e5bcc18c5f116d979e7524248495

devstack/lib/ironic

@@ -1020,7 +1020,8 @@ function install_virtualbmc {
 
     local cmd
 
-    cmd=$(which vbmcd)
+    BIN_DIR=$(get_python_exec_prefix)
+    cmd=$BIN_DIR/vbmcd
     cmd+=" --foreground"
 
     write_user_unit_file $IRONIC_VBMC_SYSTEMD_SERVICE "$cmd" "" "$STACK_USER"

devstack/upgrade/upgrade.sh

@@ -96,7 +96,7 @@ $IRONIC_BIN_DIR/ironic-dbsync --config-file=$IRONIC_CONF_FILE
 if [[ "${HOST_TOPOLOGY}" == "multinode" ]]; then
     iniset $IRONIC_CONF_FILE DEFAULT pin_release_version ${BASE_DEVSTACK_BRANCH#*/}
 else
-    ironic-dbsync online_data_migrations
+    $IRONIC_BIN_DIR/ironic-dbsync online_data_migrations
 fi
 
 ensure_started='ironic-conductor nova-compute '

zuul.d/ironic-jobs.yaml

@@ -1096,9 +1096,6 @@
           # 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:
@@ -1207,9 +1204,6 @@
           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: