[Vulkan] Require a hardware GPU in the NVIDIA Vulkan CI job

[mergennachin]

Superseded by #23240, part 1/15 of the ghstack replacement series. The current integration PR is #23254. This PR is closed in favor of the replacement; its previous description and review history are retained.

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The real-GPU Vulkan job silently fell back to SwiftShader whenever the NVIDIA ICD failed to enumerate, so 8-bit storage buffer paths and the custom-op benchmarks could pass without touching the GPU. setup-vulkan-linux-deps.sh now prefers the NVIDIA EGL ICD, installs its EGL and X11 client dependencies, and fails with ldd diagnostics instead of falling back when real-gpu is requested. test_backend.sh always requests SwiftShader, since CPU runners can ship Mesa ICDs without a usable device.

Part 1/15 of the Vulkan transformer and operator-conformance stack. This enables hardware validation for the following changes. Integration PR: #23162.

Validation: Both CI setup scripts pass bash -n; lintrunner and git diff --check pass. NVIDIA execution will be verified by this PR’s CI run.

Authored with OpenAI Codex; split planned with Claude Code.

cc @SS-JIA @manuelcandales @digantdesai @cbilgin

[pytorch-bot]

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❌ 2 New Failures, 37 Pending

As of commit 2fc9384 with merge base a318382 ():

NEW FAILURES - The following jobs have failed:

• trunk / unittest-release / macos / macos-job (gh)
  ##[error]fatal: remote error: GitLab is currently unable to handle this request due to load (ID a42bbf062840202d-IAD).
• Windows MSVC Build / build-windows-arm64 (gh)

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