[AI Generated] Fix Azure VM size mismatch skip reason message

[LiliDeng]

Problem

When a test is run with a specific VM size that is incompatible with the requested image (e.g., x86-only Standard_HC44-16rs with an Arm64 Ubuntu image), LISA showed a misleading skip reason:

"Test skipped on 'westus3' for an unknown reason. This could be due to insufficient quota..."

Root Cause

In _get_allowed_capabilities(), when not allowed_capabilities and a specific vm_size was set, the error was a generic "no vm size found..." message. Then in _get_azure_capabilities(), the else: branch unconditionally overwrote any specific error set earlier with the generic "unknown reason" fallback.

Fix

1. _get_allowed_capabilities(): When not allowed_capabilities and node_runbook.vm_size is explicitly set, emit a clear message: "Requirement mismatch: requested VM size '<size>' is unavailable in '<location>' or incompatible with current test requirements."

2. _get_azure_capabilities(): Changed else: → elif not error: so the generic "unknown reason" fallback only fires when no specific error was already populated.

Validation

Repro with Standard_HC44-16rs + 22_04-lts-arm64 image in westus3 now shows:

"Requirement mismatch: requested VM size 'Standard_HC44-16rs' is unavailable in 'westus3' or incompatible with current test requirements."

[Copilot]

Pull request overview

Improves the Azure platform capability-selection skip messaging so that VM size/image requirement mismatches report a specific, actionable reason instead of being overwritten by a generic “unknown reason” message.

Changes:

• Preserve previously computed skip reasons in _get_azure_capabilities() by only using the generic fallback when no specific error was set.
• Emit a clearer “Requirement mismatch” message in _get_allowed_capabilities() when a user explicitly requests a VM size but no capabilities are found.

[Copilot]

Consider adding an explicit remediation hint to this skip reason (e.g., verify the VM size is offered in the region and supports the requested image architecture/requirements, or choose a different size/location) so it’s immediately actionable for users.

Suggested change

	"or incompatible with current test requirements."
	"or incompatible with current test requirements. Verify that "
	"the VM size is offered in this region and supports the "
	"requested image architecture and other requirements, or "
	"choose a different VM size or location."

[github-actions]

✅ AI Test Selection — PASSED

1 test case(s) selected (view run)

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

	Count
✅ Passed	1
❌ Failed	0
⏭️ Skipped	0
Total	1

Test case details

Test Case	Status	Time (s)	Message
smoke_test (lisa_0_0)	✅ PASSED	39.747

[LiliDeng]

Just for testing purpose.