[doc][DOC-898] probe: remove MockedClassDocumenter monkey-patch in conf.py (ray-project#63197)

## Why

The Anyscale docs team is auditing `doc/source/conf.py` against current
Ray state as part of strategy work tracked in
[anyscale/docs#2064](https://github.com/anyscale/docs/pull/2064). One
finding: `conf.py` globally swaps `sphinx.ext.autodoc.ClassDocumenter`
with a `MockedClassDocumenter` subclass that suppresses the `Bases:
object` line for classes that inherit directly from `object`.

The patch was added in
[ray-project#39982](ray-project#39982) (Oct 2023). It's
a cosmetic workaround. Two reasons it may now be obsolete:

1. **Modern pydata-sphinx-theme** (Ray pins 0.14.1; current is 0.16.x)
renders base class lines differently than it did when the patch was
authored.
2. **Global monkey patches at conf.py module scope** are a fragility
liability — if a future Sphinx ClassDocumenter signature change lands,
the patch breaks the build at import. The cosmetic value should be
weighed against that ongoing maintenance cost.

## What this PR does

1. Removes the `MockedClassDocumenter` class and its global assignment
to `sphinx.ext.autodoc.ClassDocumenter`.
2. Removes the now-unused `from sphinx.ext import autodoc` import.

## How to validate

This is a probe, not a request-for-merge. The validation surfaces are:

1. **RtD PR preview build** — runs against this branch. With
`fail_on_warning: true` set in `.readthedocs.yaml`, any new Sphinx
warning means the patch was still load-bearing in a non-cosmetic way.
2. **`doc: check API doc consistency`** — premerge step that runs `make
-C doc/ html` internally. Same fail-on-warning gate.
3. **Visual diff of any API ref page** for a class that inherits
directly from `object`. If `Bases: object` reappears in those pages, the
patch was effectively suppressing visible noise — keep it. If the line
is rendered the same way (or absent) by the modern theme without the
patch, drop it.

## Possible outcomes

- **Build clean, no visible regression** → the patch is dead weight.
Drop.
- **Build clean, `Bases: object` reappears on many pages** → the patch
is doing what it claims. Keep, and add a comment explaining what would
replace it (a CSS rule on the modern theme's rendered output, or a
different autodoc filter).
- **Build fails** → the patch was load-bearing in a way nobody
documented. Revert and document.

## Status

**Draft.** Posting for visibility and validation, not for merge. Looking
for a Ray maintainer to confirm whether the cosmetic suppression is
still desired and whether there's a less-fragile mechanism to achieve
it. Justin Yu @justinvyu, Aydin Abiar @aslonnie, or Elliot Barnwell
@ebarn-anyscale would all be reasonable reviewers given recent activity
in this area.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: Douglas Strodtman <douglas@anyscale.com>

Author: dstrodtman

doc/source/conf.py

@@ -15,7 +15,6 @@
 import sphinx
 from docutils import nodes
 from jinja2.filters import FILTERS
-from sphinx.ext import autodoc
 from sphinx.ext.autosummary import generate
 from sphinx.util.inspect import safe_getattr
 
@@ -858,17 +857,6 @@ def fix_collections_code_blocks(app, docname, source):
         )
 
 
-class MockedClassDocumenter(autodoc.ClassDocumenter):
-    """Remove note about base class when a class is derived from object."""
-
-    def add_line(self, line: str, source: str, *lineno: int) -> None:
-        if line == "   Bases: :py:class:`object`":
-            return
-        super().add_line(line, source, *lineno)
-
-
-autodoc.ClassDocumenter = MockedClassDocumenter
-
 # Other sphinx docs can be linked to if the appropriate URL to the docs
 # is specified in the `intersphinx_mapping` - for example, types annotations
 # that are defined in dependencies can link to their respective documentation.