Configure ironic to use Ipmitool retries

Without this configuration, the ipmitool timeout is 1 second. This is too short
for vbmc. This commit uses the ipmitool retry feature and extends the
timeout

ironic.conf

@@ -67,3 +67,8 @@ uefi_pxe_config_template = $pybasedir/drivers/modules/ipxe_config.template
 
 [redfish]
 use_swift = false
+
+[ipmi]
+use_ipmitool_retries = true
+min_command_interval = 5
+command_retry_timeout = 15