Enable full OpenVMM test backtraces

[vyadavmsft]

Set RUST_BACKTRACE=full for upstream OpenVMM VMM test runs so panic logs include the verbose Rust backtrace requested by the OpenVMM failure message. This keeps the change scoped to the test tool environment used by cargo xflowey vmm-tests-run.

Description

Related Issue

Type of Change

• Bug fix
• New feature
• Breaking change
• Refactoring
• Documentation update

Checklist

• Description is filled in above
• No credentials, secrets, or internal details are included
• Peer review requested (if not, add required peer reviewers after raising PR)
• Tests executed and results posted below

Test Validation

Key Test Cases:

Impacted LISA Features:

Tested Azure Marketplace Images:

Test Results

Image	VM Size	Result
		PASSED / FAILED / SKIPPED

[Copilot]

Pull request overview

This PR updates the OpenVMM upstream vmm_tests runner environment so Rust panics emit verbose backtraces, improving diagnosability when upstream failure output requests RUST_BACKTRACE=full.

Changes:

• Set RUST_BACKTRACE=full (instead of 1) in the cargo/xflowey test environment used by vmm-tests-run.

[github-actions]

✅ AI Test Selection — PASSED

4 test case(s) selected (view run)

Marketplace image: canonical 0001-com-ubuntu-server-jammy 22_04-lts-gen2 latest

	Count
✅ Passed	0
❌ Failed	0
⏭️ Skipped	4
Total	4

Test case details

Test Case	Status	Time (s)	Message
verify_openvmm_restart_via_platform (lisa_0_2)	⏭️ SKIPPED	5.258	before_case skipped: This suite only applies to OpenVMM guest nodes. Actual node type: RemoteNode.
verify_openvmm_guest_boot (lisa_0_1)	⏭️ SKIPPED	5.722	before_case skipped: This suite only applies to OpenVMM guest nodes. Actual node type: RemoteNode.
verify_openvmm_stop_start_in_platform (lisa_0_3)	⏭️ SKIPPED	6.439	before_case skipped: This suite only applies to OpenVMM guest nodes. Actual node type: RemoteNode.
verify_openvmm_upstream_vmm_tests (lisa_0_0)	⏭️ SKIPPED	12.471	before_case skipped: OpenVMM upstream tests are not implemented for Ubuntu