Fix UI issue 5777 Root disk size is not shown as 'Disk Size' on VM deployment. (#5796)

In the UI, when selecting a service offering that has a root disk enforced, stills show the root disk size of the template (or the custom size gave by the user). This PR fixes this issue, that thas been reported in #5777.
Fixes: #5777

Author: GabrielBrascher

ui/src/views/compute/DeployVM.vue

@@ -1133,7 +1133,9 @@ export default {
         this.vm.hostname = host.name
       }
 
-      if (this.diskSize) {
+      if (this.serviceOffering.rootdisksize) {
+        this.vm.disksizetotalgb = this.serviceOffering.rootdisksize
+      } else if (this.diskSize) {
         this.vm.disksizetotalgb = this.diskSize
       }