[Task]: Remove DataFrame cruft from Python Docs precommit

[TheNeuralBit]

What needs to happen?

The PythonDocs log is filled with a bunch of warning logs from the DataFrame docs, which are all ignored. This makes it very hard to pick out the actual error when one occurs. For example, from https://ci-beam.apache.org/job/beam_PreCommit_PythonDocs_Phrase/58:

15:21:58 /home/jenkins/jenkins-slave/workspace/beam_PreCommit_PythonDocs_Phrase/src/sdks/python/test-suites/tox/pycommon/build/srcs/sdks/python/target/.tox-py38-docs/py38-docs/lib/python3.8/site-packages/apache_beam/dataframe/frames.py:docstring of apache_beam.dataframe.frames.DeferredDataFrame.to_stata:91: WARNING: Definition list ends without a blank line; unexpected unindent.
15:21:58 /home/jenkins/jenkins-slave/workspace/beam_PreCommit_PythonDocs_Phrase/src/sdks/python/test-suites/tox/pycommon/build/srcs/sdks/python/target/.tox-py38-docs/py38-docs/lib/python3.8/site-packages/apache_beam/dataframe/io.py:docstring of apache_beam.dataframe.io.to_stata:91: WARNING: Definition list ends without a blank line; unexpected unindent.
15:21:58 /home/jenkins/jenkins-slave/workspace/beam_PreCommit_PythonDocs_Phrase/src/sdks/python/test-suites/tox/pycommon/build/srcs/sdks/python/target/.tox-py38-docs/py38-docs/lib/python3.8/site-packages/apache_beam/ml/inference/base.py:docstring of apache_beam.ml.inference.base.RunInference:5: WARNING: Unexpected indentation.
15:22:24 /home/jenkins/jenkins-slave/workspace/beam_PreCommit_PythonDocs_Phrase/src/sdks/python/test-suites/tox/pycommon/build/srcs/sdks/python/target/.tox-py38-docs/py38-docs/lib/python3.8/site-packages/apache_beam/dataframe/frames.py:docstring of apache_beam.dataframe.frames.DeferredSeries:1: WARNING: py:class reference target not found: apache_beam.dataframe.frames.DeferredDataFrameOrSeries
15:22:24 /home/jenkins/jenkins-slave/workspace/beam_PreCommit_PythonDocs_Phrase/src/sdks/python/test-suites/tox/pycommon/build/srcs/sdks/python/target/.tox-py38-docs/py38-docs/lib/python3.8/site-packages/apache_beam/dataframe/frames.py:docstring of apache_beam.dataframe.frames.DeferredSeries.name:: WARNING: py:class reference target not found: label

There's one actual error for the ml package in there.

We should just drop the dataframe warnings from the log, since they're ignored anyway.

Issue Priority

Priority: 2

Issue Component

Component: dsl-dataframe