compute: fix preview=false updates for OrganizationSecurityPolicyRule

[sumanth-g31]

Fixes hashicorp/terraform-provider-google#27885

Summary

This change adds send_empty_value: true to the preview field of
OrganizationSecurityPolicyRule.

Without this annotation, the generated Terraform provider treats
preview = false as an empty value and omits it from create and update
requests. As a result, users cannot reliably update a rule from:

preview = true

to

preview = false

because the PATCH request does not include the preview field.

Root cause

The generated provider code used the condition:

!tpgresource.IsEmptyValue(reflect.ValueOf(v))

Since IsEmptyValue() considers the boolean value false to be empty,
preview = false was filtered out and never added to the request body.

Adding send_empty_value: true causes Magic Modules to generate:

ok || !reflect.DeepEqual(v, previewProp)

which preserves explicitly configured false values.

compute: fixed an issue where `preview = false` updates for `google_compute_organization_security_policy_rule` were omitted from API requests.

Verification

• Added send_empty_value: true to the preview property in OrganizationSecurityPolicyRule.yaml.
• Regenerated the Terraform provider.
• Verified that the generated resource_compute_organization_security_policy_rule.go
  now includes preview whenever it is explicitly configured, including false.
• Verified that the generated behavior now matches the existing implementation for
  SecurityPolicyRule and RegionSecurityPolicyRule.

Background

I initially investigated this issue in hashicorp/terraform-provider-google and opened hashicorp/terraform-provider-google#28000.

As suggested by @melinath in that PR, this fix has been moved to Magic Modules since the provider code is generated from this repository.

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