[SPARK-8765] [MLLIB] [PYTHON] removed flaky python PIC test

See failure: [https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/36133/console]

CC yanboliang  mengxr

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

Closes #7164 from jkbradley/pic-python-test and squashes the following commits:

156d55b [Joseph K. Bradley] removed flaky python PIC test

python/pyspark/mllib/clustering.py

@@ -288,16 +288,12 @@ class PowerIterationClusteringModel(JavaModelWrapper, JavaSaveable, JavaLoader):
     >>> model = PowerIterationClustering.train(rdd, 2, 100)
     >>> model.k
     2
-    >>> sorted(model.assignments().collect())
-    [Assignment(id=0, cluster=1), Assignment(id=1, cluster=0), ...
     >>> import os, tempfile
     >>> path = tempfile.mkdtemp()
     >>> model.save(sc, path)
     >>> sameModel = PowerIterationClusteringModel.load(sc, path)
     >>> sameModel.k
     2
-    >>> sorted(sameModel.assignments().collect())
-    [Assignment(id=0, cluster=1), Assignment(id=1, cluster=0), ...
     >>> from shutil import rmtree
     >>> try:
     ...     rmtree(path)