test: add test for MIG mixed mode

[runzhen]

What this PR does / why we need it:
Add a test case for MIG mixed mode.

Which issue(s) this PR fixes:

Fixes #

[Copilot]

Pull request overview

Adds an e2e scenario to validate NVIDIA MIG mixed strategy behavior (resource-type-specific advertising like nvidia.com/mig-1g.10gb) on Ubuntu 24.04 GPU nodes, and updates the shared GPU scheduling validator to work with arbitrary GPU resource names.

Changes:

• Extend ValidateGPUWorkloadSchedulable to accept a resourceName parameter and use it for both readiness wait and pod resource limits.
• Update existing GPU e2e scenarios to pass "nvidia.com/gpu" explicitly.
• Add a new Ubuntu 24.04 MIG Mixed scenario that validates MIG instance creation, resource advertising for nvidia.com/mig-1g.10gb, and workload schedulability.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
e2e/validators.go	Generalize GPU workload scheduling validator to support MIG-specific resource names.
e2e/scenario_gpu_managed_experience_test.go	Update validator call sites and add a new MIG Mixed scenario covering MIG resource advertising + scheduling.
e2e/scenario_gpu_daemonset_test.go	Update daemonset scenario to use the new validator signature.