Fix shard and physical height mismatch in ttnn.convert_to_chw tests

[esmalTT]

Ticket

• Conv ops/models #17247

What's changed

• Fix validation in pytest tests/ttnn/unit_tests/operations/test_convert_to_chw.py::test_convert_to_chw
• Consolidate CB indices in ttnn.convert_to_chw

Checklist

• Commit that flips the check to TT_FATAL + whatever fix ops/tests/models need
• Post-commit all passes (UNet Shallow only, with TT_FATAL): https://github.com/tenstorrent/tt-metal/actions/runs/13019539000
• Nightly fast dispatch passes (UNet Shallow only, with TT_FATAL): https://github.com/tenstorrent/tt-metal/actions/runs/13019542734
• Post-commit all passes (with TT_ASSERT): https://github.com/tenstorrent/tt-metal/actions/runs/13037856394
• Nightly fast dispatch passes (with TT_ASSERT): https://github.com/tenstorrent/tt-metal/actions/runs/13037864680

Note: The failure was only in a single test, and this test is confirmed to be now passing. The only model using this op is UNet Shallow, its tests are passing.