compute: randomize sub-resource names in external_vpn_gateway sample

[shuyama1]

Fixes TestAccComputeExternalVpnGateway_externalVpnGatewayExample by parameterizing sub-resource names (vpn tunnels, subnets, router interfaces, and router peers) with ResourceIdVars in ExternalVpnGateway.yaml and external_vpn_gateway.tf.tmpl.

This ensures they receive dynamic random string suffixes during acceptance test execution, preventing HTTP 409 Conflict errors when sub-resources with hardcoded names already exist in the test project.

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit 5571f0e:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	2 files changed, 37 insertions(+), 21 deletions(-)
google-beta provider	View Diff	2 files changed, 37 insertions(+), 21 deletions(-)
Open in Cloud Shell	View Diff	1 file changed, 8 insertions(+), 8 deletions(-)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
1550	1453	95	2

Affected Service Packages

• compute

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Step 1: Replaying Mode

Action taken

Found 2 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit.

Click here to see the affected tests

• TestAccComputeInstanceFromMachineImage_diffProject
• TestAccComputeSecurityPolicy_withPreconfiguredWafConfig

View the replaying VCR build log

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Step 2: Recording Mode

Recording Mode	Replaying Rerun	Test Name
❌ Error · Log	-	TestAccComputeInstanceFromMachineImage_diffProject
❌ Error · Log	-	TestAccComputeSecurityPolicy_withPreconfiguredWafConfig

Caution

Issues requiring attention before PR completion

🔴 Initial Recording Failed: Some tests failed during the recording step. See the table above for details.

Please address these issues to complete your PR. If you believe these detections are incorrect or unrelated to your change, please raise the concern with your reviewer.

View the recording VCR build log or the debug logs folder for detailed results.

@shuyama1 VCR tests complete for 5571f0e!