CI: Patch to fix CI jobs in bugfix/stable branches

Composite of effective changes from:
I36f8fc8130ed914e8a2c2a11c9679144d931ad73
Ia6dac22081c92bbccc803f233dd53740f6b48abb
I820bba1347954b659fd7469ed542f98ef0a6eaf0

Ultimately to reduce CI VM count in terms of memory
utilization and disk utilization in order to get
consumption into a safe range to prevent
out of memory and out of disk space conditions.

Also disables automated erasure on one of the jobs
where it was disabled on other branches as it is
already tested elsewhere in the gate.

Change-Id: Ic9f3ddc9cd48c5a973996a4136d9832f869c0b08

playbooks/legacy/grenade-dsvm-ironic-multinode-multitenant/run.yaml

@@ -146,7 +146,7 @@
           export DEVSTACK_GATE_IRONIC_BUILD_RAMDISK=0
           export DEVSTACK_LOCAL_CONFIG+=$'\n'"IRONIC_INSPECTOR_BUILD_RAMDISK=False"
 
-          export DEVSTACK_LOCAL_CONFIG+=$'\n'"IRONIC_VM_COUNT=7"
+          export DEVSTACK_LOCAL_CONFIG+=$'\n'"IRONIC_VM_COUNT=4"
 
           # Ensure the ironic-vars-EARLY file exists
           touch ironic-vars-early

playbooks/legacy/grenade-dsvm-ironic/run.yaml

@@ -93,7 +93,7 @@
           export DEVSTACK_LOCAL_CONFIG+=$'\n'"IRONIC_AUTOMATED_CLEAN_ENABLED=False"
           export DEVSTACK_GATE_TEMPEST_REGEX=test_server_basic_ops
 
-          export DEVSTACK_LOCAL_CONFIG+=$'\n'"IRONIC_VM_COUNT=7"
+          export DEVSTACK_LOCAL_CONFIG+=$'\n'"IRONIC_VM_COUNT=4"
 
           # Ensure the ironic-vars-EARLY file exists
           touch ironic-vars-early

zuul.d/ironic-jobs.yaml

@@ -107,7 +107,7 @@
         IRONIC_ENABLED_DEPLOY_INTERFACES: "iscsi,direct,ansible"
         IRONIC_ENABLED_RESCUE_INTERFACES: "fake,agent,no-rescue"
         IRONIC_RPC_TRANSPORT: json-rpc
-        IRONIC_VM_COUNT: 6
+        IRONIC_VM_COUNT: 4
         IRONIC_VM_VOLUME_COUNT: 2
         # We're using a lot of disk space in this job. Some testing nodes have
         # a small root partition, so use /opt which is mounted from a bigger
@@ -141,6 +141,7 @@
         IRONIC_DEPLOY_DRIVER: redfish
         IRONIC_ENABLED_HARDWARE_TYPES: redfish
         IRONIC_VM_COUNT: 2
+        IRONIC_AUTOMATED_CLEAN_ENABLED: False
 
 - job:
     name: ironic-tempest-pxe_ipmitool-postgres
@@ -251,6 +252,7 @@
         IRONIC_AUTOMATED_CLEAN_ENABLED: False
         SWIFT_ENABLE_TEMPURLS: True
         SWIFT_TEMPURL_KEY: secretkey
+        IRONIC_VM_COUNT: 1
       devstack_plugins:
         ironic-inspector: https://opendev.org/openstack/ironic-inspector
       devstack_services: