Update on "Remove old QAT APIs"

**Summary:** As a follow-up to #2641,
which deprecated the old QAT APIs in 0.13.0, we remove them now
in the next release 0.15.0.

Fixes #2630.

**Test Plan:** CI

[ghstack-poisoned]

Author: andrewor14

torchao/quantization/prototype/qat/api.py

@@ -1,5 +1,7 @@
 from torchao.quantization.qat.api import (
     ComposableQATQuantizer,
+)
+from torchao.quantization.qat.api import (
     IntxFakeQuantizeConfig as FakeQuantizeConfig,
 )
 

torchao/quantization/quant_api.py

@@ -148,7 +148,6 @@
     "int8_dynamic_activation_int8_semi_sparse_weight",
     "int4_weight_only",
     "int8_weight_only",
-    "intx_quantization_aware_training",
     "float8_weight_only",
     "uintx_weight_only",
     "fpx_weight_only",

torchao/utils.py

@@ -11,7 +11,7 @@
 from functools import reduce
 from importlib.metadata import version
 from math import gcd
-from typing import Any, Callable, Optional, Type
+from typing import Any, Callable, Optional
 
 import torch
 import torch.nn.utils.parametrize as parametrize