[SPARK-14812][ML][MLLIB][PYTHON] Experimental, DeveloperApi annotation audit for ML

## What changes were proposed in this pull request?

General decisions to follow, except where noted:
* spark.mllib, pyspark.mllib: Remove all Experimental annotations.  Leave DeveloperApi annotations alone.
* spark.ml, pyspark.ml
** Annotate Estimator-Model pairs of classes and companion objects the same way.
** For all algorithms marked Experimental with Since tag <= 1.6, remove Experimental annotation.
** For all algorithms marked Experimental with Since tag = 2.0, leave Experimental annotation.
* DeveloperApi annotations are left alone, except where noted.
* No changes to which types are sealed.

Exceptions where I am leaving items Experimental in spark.ml, pyspark.ml, mainly because the items are new:
* Model Summary classes
* MLWriter, MLReader, MLWritable, MLReadable
* Evaluator and subclasses: There is discussion of changes around evaluating multiple metrics at once for efficiency.
* RFormula: Its behavior may need to change slightly to match R in edge cases.
* AFTSurvivalRegression
* MultilayerPerceptronClassifier

DeveloperApi changes:
* ml.tree.Node, ml.tree.Split, and subclasses should no longer be DeveloperApi

## How was this patch tested?

N/A

Note to reviewers:
* spark.ml.clustering.LDA underwent significant changes (additional methods), so let me know if you want me to leave it Experimental.
* Be careful to check for cases where a class should no longer be Experimental but has an Experimental method, val, or other feature.  I did not find such cases, but please verify.

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #14147 from jkbradley/experimental-audit.

1 files changed, 0 insertions, 6 deletions

diff --git a/python/pyspark/mllib/classification.py b/python/pyspark/mllib/classification.py
index 3734f87405..9f53ed0982 100644
--- a/python/pyspark/mllib/classification.py
+++ b/python/pyspark/mllib/classification.py
@@ -48,8 +48,6 @@ class LinearClassificationModel(LinearModel):
     @since('1.4.0')
     def setThreshold(self, value):
         """
-        .. note:: Experimental
-
         Sets the threshold that separates positive predictions from
         negative predictions. An example with prediction score greater
         than or equal to this threshold is identified as a positive,
@@ -62,8 +60,6 @@ class LinearClassificationModel(LinearModel):
     @since('1.4.0')
     def threshold(self):
         """
-        .. note:: Experimental
-
         Returns the threshold (if any) used for converting raw
         prediction scores into 0/1 predictions. It is used for
         binary classification only.
@@ -73,8 +69,6 @@ class LinearClassificationModel(LinearModel):
     @since('1.4.0')
     def clearThreshold(self):
         """
-        .. note:: Experimental
-
         Clears the threshold so that `predict` will output raw
         prediction scores. It is used for binary classification only.
         """