[tests] fix hot-swapping recompilation with different_shapes_for_compilation
`test_hotswapping_compiled_model_linear` and
`test_hotswapping_compiled_model_both_linear_and_other` failed for every model
setting `different_shapes_for_compilation`, e.g.:
RecompileError: tensor 'hidden_states' size mismatch at index 1.
expected 16, actual 32
The dummy inputs are `(batch, height * width, channels)` with `channels = 16`
and the first traced shape is `(4, 4)`, so the image sequence length equals the
channel count. Duck shaping assigns both dims the same symbol, which `img_in`
(an `nn.Linear` with constant `in_features`) then specializes to 16, forcing a
recompile on the next shape.
`use_duck_shape = False` was already set in `test_compile_on_different_shapes`
and `test_hotswapping_compile_on_different_shapes` (#11327) but the other two
multi-shape hot-swapping tests were missed. Move it into
`_check_model_hotswap` so all of them are covered, and drop the now-redundant
duplicate.
Also drop the two `xfail(strict=True)` markers on
`TestQwenImageTransformerLoRAHotSwap` that were masking this bug.
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
