[George Adams (gdams)]

Native validation stack

Top layer of stack #2666: #2663 → this PR.

Stacked above #2663 so Azure Linux 4 CI exercises the provider-aware ML-DSA fallback using merged OpenSSL support commit 38f583a66fdf from microsoft/go-crypto-openssl#109.

The stack lands on microsoft/release-branch.go1.27. Use the native stack merge flow.

Summary

• Add five Azure Linux 4.0 amd64 innerloop configurations: Go crypto, system crypto, cgo-less system crypto, and FIPS for both system crypto modes.
• Register the published Azure Linux 4.0 CI image and select it for azurelinux4 jobs.
• Regenerate public PR/outerloop and internal rolling/innerloop container resources.
• Preserve all existing Azure Linux 3.0 and other platform coverage and packaging.
• CI configuration changes only: no new test files or README changes.

Equivalent main coverage is #2651.

Validation

• Existing pipeline generation reproducibility test passes.
• Verified exactly five amd64 jobs with the expected crypto/cgo/FIPS combinations.
• Removing only Azure Linux 4 additions reproduces the original matrix, routing, and container resources byte-for-byte.
• git diff --check passes.
• The underlying merged-SHA fix passes actual Azure Linux 4 SymCrypt external-mu tests in cgo/non-cgo and FIPS configurations; this PR runs the full CI jobs.

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