[SPARK-31681][ML][PYSPARK] Python multiclass logistic regression evaluate should return LogisticRegressionSummary

### What changes were proposed in this pull request?
Return LogisticRegressionSummary for multiclass logistic regression evaluate in PySpark

### Why are the changes needed?
Currently we have
```
    since("2.0.0")
    def evaluate(self, dataset):
        if not isinstance(dataset, DataFrame):
            raise ValueError("dataset must be a DataFrame but got %s." % type(dataset))
        java_blr_summary = self._call_java("evaluate", dataset)
        return BinaryLogisticRegressionSummary(java_blr_summary)
```
we should return LogisticRegressionSummary for multiclass logistic regression

### Does this PR introduce _any_ user-facing change?
Yes
return LogisticRegressionSummary instead of BinaryLogisticRegressionSummary for multiclass logistic regression in Python

### How was this patch tested?
unit test

Closes #28503 from huaxingao/lr_summary.

Authored-by: Huaxin Gao <[email protected]>
Signed-off-by: Sean Owen <[email protected]>

Author: huaxingao

python/pyspark/ml/classification.py

@@ -932,7 +932,10 @@ def evaluate(self, dataset):
         if not isinstance(dataset, DataFrame):
             raise ValueError("dataset must be a DataFrame but got %s." % type(dataset))
         java_blr_summary = self._call_java("evaluate", dataset)
-        return BinaryLogisticRegressionSummary(java_blr_summary)
+        if self.numClasses <= 2:
+            return BinaryLogisticRegressionSummary(java_blr_summary)
+        else:
+            return LogisticRegressionSummary(java_blr_summary)
 
 
 class LogisticRegressionSummary(JavaWrapper):

python/pyspark/ml/tests/test_training_summary.py

@@ -21,7 +21,8 @@
 if sys.version > '3':
     basestring = str
 
-from pyspark.ml.classification import LogisticRegression
+from pyspark.ml.classification import BinaryLogisticRegressionSummary, LogisticRegression, \
+    LogisticRegressionSummary
 from pyspark.ml.clustering import BisectingKMeans, GaussianMixture, KMeans
 from pyspark.ml.linalg import Vectors
 from pyspark.ml.regression import GeneralizedLinearRegression, LinearRegression
@@ -149,6 +150,7 @@ def test_binary_logistic_regression_summary(self):
         # test evaluation (with training dataset) produces a summary with same values
         # one check is enough to verify a summary is returned, Scala version runs full test
         sameSummary = model.evaluate(df)
+        self.assertTrue(isinstance(sameSummary, BinaryLogisticRegressionSummary))
         self.assertAlmostEqual(sameSummary.areaUnderROC, s.areaUnderROC)
 
     def test_multiclass_logistic_regression_summary(self):
@@ -187,6 +189,8 @@ def test_multiclass_logistic_regression_summary(self):
         # test evaluation (with training dataset) produces a summary with same values
         # one check is enough to verify a summary is returned, Scala version runs full test
         sameSummary = model.evaluate(df)
+        self.assertTrue(isinstance(sameSummary, LogisticRegressionSummary))
+        self.assertFalse(isinstance(sameSummary, BinaryLogisticRegressionSummary))
         self.assertAlmostEqual(sameSummary.accuracy, s.accuracy)
 
     def test_gaussian_mixture_summary(self):