Reduce ESP partition size in deployment image

It does not fit into 550MiB partition created by Ironic Python Agent.
This is relevant when provisioning software RAID UEFI enabled servers.

Author: cityofships

etc/kayobe/stackhpc-overcloud-dib.yml

@@ -102,7 +102,7 @@ stackhpc_overcloud_dib_block_device_config_uefi_lvm: |
       partitions:
         - name: ESP
           type: 'EF00'
-          size: 550MiB
+          size: 500MiB
           mkfs:
             type: vfat
             mount: