add_metric method is marked as Permanently disabled
I changed the version from **2.15.0.post1** to **2.15.0** and this feature is supported. 
I wonder if the feature will be re-supported in a future release? After testing, I found that this issue is caused by the introduction of keras3, and may be ready to deprecate this method in new versions of keras.
### Issue type

Feature Request

### Have you reproduced the bug with TensorFlow Nightly?

Yes

### Source

source

### TensorFlow version

tf 2.15

### Custom code

Yes

### OS platform and distribution

Linux Ubuntu 22

### Mobile device

_No response_

### Python version

3.11

### Bazel version

_No response_

### GCC/compiler version

_No response_

### CUDA/cuDNN version

_No response_

### GPU model and memory

_No response_

### Current behavior?

Why is this method not being used, and are there any alternatives? I don't even know in which version it was retired.

### Standalone code to reproduce the issue

```shell
@keras_export(["keras.Layer", "keras.layers.Layer"])
class Layer(BackendLayer, Operation):
    ...
    def add_metric(self):
        # Permanently disabled
        raise NotImplementedError
    ...
```


### Relevant log output

_No response_