Remove VMware-specific checks in ProvisionMethod==image in host creation

Removes an experimental check of the compute_attributes when using "image"-based
host creation. The backend providers need different values.

VMware for example needs the image_id as UUID, see the example file
in examples/host/vmware_imagebased_host.tf

Refs #125

foreman/resource_foreman_host.go

@@ -1051,42 +1051,10 @@ func resourceForemanHostCreate(ctx context.Context, d *schema.ResourceData, meta
 	log.Debugf("ForemanHost: [%+v]", h)
 	hostRetryCount := d.Get("retry_count").(int)
 
-	// This query allows to distinguish between different compute resource providers.
-	// See below how it is used in VMware and its usage of UUIDs for images.
-
-	// Sometimes failes with '{"message":"undefined method `resource_pools' for nil:NilClass"}'
-	// Source: https://github.com/fog/fog-vsphere/blob/ca07a0d41f1d1d07e4d791887c0875523fb91da8/lib/fog/vsphere/models/compute/cluster.rb#L15
-	// computeResource, readErr := client.ReadComputeResource(ctx, *h.ComputeResourceId)
-	// if readErr != nil {
-	// 	return diag.FromErr(readErr)
-	// }
-	// log.Debugf("computeResource: [%+v]", computeResource)
-
-	var diags diag.Diagnostics
-	if h.ProvisionMethod == "image" { // && strings.ToLower(computeResource.Provider) == "vmware" {
-		// TODO: is this only vmware specific? Do other providers use the UUID for their images as well?
-		log.Debugf("ProvisionMethod is image, provider is vmware - checking ComputeAttributes")
-		if h.ComputeAttributes == nil {
-			diag := diag.Diagnostic{
-				Severity: diag.Error,
-				Summary:  "Provision method 'image' needs image_id in compute_attributes",
-				Detail:   "When choosing the provision method 'image' you need to provide the image UUID in the 'compute_attributes' (JSON) field 'image_id'.",
-			}
-			diags = append(diags, diag)
-			return diags
-
-		} else if _, ok := h.ComputeAttributes["image_id"]; !ok {
-			log.Debugf("image_id is not in ComputeAttributes,")
-			diag := diag.Diagnostic{
-				Severity: diag.Error,
-				Summary:  "Compute attributes need to contain the 'image_id' field when using image-based provisioning",
-				Detail: fmt.Sprintf("You defined the JSON for 'compute_attributes' for host %s, but did not provide the field 'image_id' "+
-					"which must be the image UUID you wish to use.", h.Name),
-			}
-			diags = append(diags, diag)
-			return diags
-		}
-	}
+	// See commit ad2b5890f09645513b520f12291546f26b812c96 for an experimental implementation
+	// for checks of the "computeAttributes" field, when using ProvisionMethod=image.
+	// The feature was removed because it was VMware-specific and the test on the backend provider
+	// could not yet be implemented (via client.ReadComputeResource -> computeResource.Provider)
 
 	createdHost, createErr := client.CreateHost(ctx, h, hostRetryCount)
 	if createErr != nil {