### What changes were proposed in this pull request?
It increases the timeout for `StreamingLinearRegressionWithTests.test_train_prediction`
```
Traceback (most recent call last):
File "/home/jenkins/workspace/SparkPullRequestBuilder3/python/pyspark/mllib/tests/test_streaming_algorithms.py", line 503, in test_train_prediction
self._eventually(condition)
File "/home/jenkins/workspace/SparkPullRequestBuilder3/python/pyspark/mllib/tests/test_streaming_algorithms.py", line 69, in _eventually
lastValue = condition()
File "/home/jenkins/workspace/SparkPullRequestBuilder3/python/pyspark/mllib/tests/test_streaming_algorithms.py", line 498, in condition
self.assertGreater(errors[1] - errors[-1], 2)
AssertionError: 1.672640157855923 not greater than 2
```
This could likely happen when the PySpark tests run in parallel and it become slow.
### Why are the changes needed?
To make the tests less flaky. Seems it's being reported multiple times:
https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/123144/consoleFullhttps://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/123146/testReport/https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/123141/testReport/https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/123142/testReport/
### Does this PR introduce _any_ user-facing change?
No, test-only.
### How was this patch tested?
Jenkins will test it out.
Closes#28701 from HyukjinKwon/SPARK-29137.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
64cb6f7066