chore(settings): remove the bmm attention methods

Batch matrix-matrix and Dynamic Attention BMM applied a legacy Attention
processor to pipe.unet, which a diffusion transformer does not have, so
they served unet models alone and said nothing elsewhere. The choices, the
processor and its slice helper are removed, an unrecognized method now
warns rather than selecting nothing, and a stored value is rewritten to
Scaled-Dot-Product on load.

test/test-attention-router.py

@@ -443,6 +443,27 @@ def test_attention_slicing_follows_the_choice():
     return True
 
 
+def test_removed_attention_methods_are_gone():
+    from modules import shared_items
+    from modules import options_handler
+    from modules import sd_hijack_dynamic_atten
+
+    removed = ['Batch matrix-matrix', 'Dynamic Attention BMM']
+    choices = shared_items.list_crossattention()
+    assert not [name for name in removed if name in choices], choices
+    for name in removed:
+        data = {'cross_attention_optimization': name}
+        migrated = options_handler.migrate_removed_values(data)
+        assert data['cross_attention_optimization'] == 'Scaled-Dot-Product', data
+        assert len(migrated) == 1, migrated
+    kept = {'cross_attention_optimization': 'xFormers'}
+    assert options_handler.migrate_removed_values(kept) == [], 'a live choice is left alone'
+    assert kept['cross_attention_optimization'] == 'xFormers', kept
+    assert not hasattr(sd_hijack_dynamic_atten, 'DynamicAttnProcessorBMM'), 'the bmm processor is removed'
+    assert hasattr(sd_hijack_dynamic_atten, 'dynamic_scaled_dot_product_attention'), 'the sliced sdpa path stays'
+    return True
+
+
 def test_escape_hatch_bypasses_the_router():
     from modules import devices
     saved_sdpa = torch.nn.functional.scaled_dot_product_attention
@@ -516,6 +537,7 @@ def run_all():
         test_debug_observe_logs_each_route_once,
         test_reapply_options_cover_declared_backend_options,
         test_attention_slicing_follows_the_choice,
+        test_removed_attention_methods_are_gone,
         test_escape_hatch_bypasses_the_router,
     ]:
         run_test(cat, fn)