tgc: fix TestAccDatastreamPrivateConnection test

[zli82016]

assert_test_files.go:138: TestAccDatastreamPrivateConnection_datastreamPrivateConnectionPscInterfaceExample_step1: Failed after 5 attempts. First real error: retryable: missing fields: [psc_interface_config.network_attachment]

Identified the Root Cause: The API was not returning pscInterfaceConfig in the CAI asset, which violated the exactly_one_of constraint in the Terraform provider schema (requiring either psc_interface_config or vpc_peering_config).

Applied Fixes:

Marked pscInterfaceConfig as is_missing_in_cai: true in PrivateConnection.yaml.
Added a tgc_decoder to inject a dummy pscInterfaceConfig block when both are missing, ensuring the generated HCL is valid for plan.

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit fc6b6ab:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
terraform-google-conversion	View Diff	2 files changed, 19 insertions(+)