[ET-VK][qconv] Fix depthwise weight_sums sum dimension

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK][ez][qconv] Add auto-selection to prefer im2col for q8ta_conv2d #17568
• [ET-VK][q8ta] Fix addmm arg indexing in QuantizedLinearMatch #17567
• [ET-VK][q8ta] Add q8ta_linear_gemv op for batch-1 int8 linear #17566
• [ET-VK][q8ta] Add q8ta_linear operator for int8 quantized linear #17565
• [ET-VK][export] Update tensor representation sync logic to allow for flexibility in memory layouts #17564
• [ET-VK] Support different input layouts in q8ta_binary operator #17563
• [ET-VK][ez] Always partition batch norm as it will be fused #17508
• [ET-VK] Add fused q8ta_relu unary operator for int8x4 tensors #17507
• [ET-VK][qconv] Add apply_relu support to q8ta conv operators #17506
• [ET-VK][qconv] Pad weight_sums buffer to multiple-of-4 alignment #17505
• -> [ET-VK][qconv] Fix depthwise weight_sums sum dimension #17504

The weight_sums tensor stores per-output-channel sums of quantized weight values, used to apply activation zero point correction during integer accumulation. For depthwise convolutions, the weight tensor is reshaped to (H, W, OC), but the sum was unconditionally computed along dim=1 (the W dimension). This produced a tensor of shape (H, OC) instead of (OC,), causing incorrect zero point correction and corrupted depthwise conv output.

Fix by branching on is_depthwise_conv to sum over dims (0, 1) for the (H, W, OC) layout.

Differential Revision: D93511635

[pytorch-bot]

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❌ 3 New Failures, 2 Unrelated Failures

As of commit 8bf97f2 with merge base 7b843e4 ():

NEW FAILURES - The following jobs have failed:

• pull / test-openvino-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 26df0a6828645668f12954de2e0f296b1199f8cbc09f823c4847c3e0308fe4dc /exec failed with exit code 1
• pull / unittest-arm-backend-with-no-deps (test_pytest_ops_tosa) / linux-job (gh)
  RuntimeError: Command docker exec -t 9c5e732bb57b6961cd8864530efa7169ca23fe6a37c42cb008709b5b10926ceb /exec failed with exit code 1
• pull / unittest-nxp-neutron / linux-job (gh)
  RuntimeError: Command docker exec -t 6737e6b24f1e9ee3bc41f634644affd6b8fcb35131a1e358ac3a0e9d2fddcc5a /exec failed with exit code 1

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• Test CUDA Builds / export-model-cuda-artifact (google, gemma-3-4b-it, quantized-int4-tile-packed) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
• Test CUDA Builds / export-model-cuda-artifact (nvidia, parakeet-tdt, non-quantized) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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