Remove duplicate fuse_batch_norm_with_linear target (#24213)

`backends/transforms/targets.bzl` defines the
`fuse_batch_norm_with_linear` `python_library` twice (lines 138 and
152). The first copy comes from #24192. The second came in with the
squash of #24193, whose branch picked up the block again when it was
merged with `main`.

Buck refuses to register the same target twice, so any command that
loads `//backends/transforms/...` fails:

```
error: Attempted to register target root//backends/transforms:fuse_batch_norm_with_linear twice
```

This breaks `unittest-buck` on `main` and on open PRs.

This change deletes the second, identical definition. No other targets
in the file are duplicated.

### Test plan
- Checked that `targets.bzl` now defines each target name once.
- CI: `unittest-buck` should get past the `buck2 query` step.

Author: JakeStevens

backends/transforms/targets.bzl

@@ -148,20 +148,6 @@ def define_common_targets():
         ],
     )
 
-    runtime.python_library(
-        name = "fuse_batch_norm_with_linear",
-        srcs = ["fuse_batch_norm_with_linear.py"],
-        visibility = [
-            "//executorch/backends/...",
-        ],
-        deps = [
-            ":utils",
-            "//caffe2:torch",
-            "//executorch/exir:pass_base",
-            "//executorch/exir/dialects:lib",
-        ],
-    )
-
     runtime.python_library(
         name = "fuse_conv_with_clamp",
         srcs = ["fuse_conv_with_clamp.py"],