Remove tensorboard mapping from our default mapping (#19673)

`torch.utils.tensorboard` imports `tensorboard` (or dies trying). The
original intent is "if a file imports it, it should receive a dependency
on `tensorboard`". Unfortunately the actual behavior is that _only_
tensorboard is inferred (and not `torch`). Worse, an import from
`tensorboard` is now ambiguous (because it's missing from the value).

So we'll remove it and cherry-pick to 2.17.x (when it was introduced).
Later we can fix the underlying issue of being able to model an import
mapping to multiple packages.

See #19672

src/python/pants/backend/python/dependency_inference/default_module_mapping.py

@@ -241,7 +241,6 @@
     "snowflake-sqlalchemy": ("snowflake.sqlalchemy",),
     "strawberry-graphql": ("strawberry",),
     "streamlit-aggrid": ("st_aggrid",),
-    "tensorboard": ("torch.utils.tensorboard",),
     "unleashclient": ("UnleashClient",),
     "websocket-client": ("websocket",),
 }