deprecate v1 of IntxWeightOnlyConfig

[vkuzo]

Summary:

deprecate v1 of IntxWeightOnlyConfig and delete all callsites

Test Plan: CI

Reviewers:

Subscribers:

Tasks:

Tags:

[vkuzo]

Stack from ghstack (oldest at bottom):

• deprecate v1 of Int4WeightOnlyConfig #3513
• -> deprecate v1 of IntxWeightOnlyConfig #3512
• deprecate v1 of Int8DynamicActivationIntxWeightConfig #3511

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/ao/3512

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✅ You can merge normally! (2 Unrelated Failures)

As of commit 85be334 with merge base 23a58c0 ():

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• Run Regression Tests / test (CUDA 2.8, linux.g5.12xlarge.nvidia.gpu, torch==2.8.0, cuda, 12.6) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

BROKEN TRUNK - The following job failed but was present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Run Regression Tests / test-nightly (CUDA Nightly, linux.g5.12xlarge.nvidia.gpu, --pre torch --index-url https://downloa... / linux-job (gh) (trunk failure)
  test/test_low_bit_optim.py::TestFSDP2::test_fsdp2

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