[SPARK-13613][ML] Provide ignored tests to export test dataset into CSV format

## What changes were proposed in this pull request?
Provide ignored test cases to export the test dataset into CSV format in ```LinearRegressionSuite```, ```LogisticRegressionSuite```, ```AFTSurvivalRegressionSuite``` and ```GeneralizedLinearRegressionSuite```, so users can validate the training accuracy compared with R's glm, glmnet and survival package.
cc mengxr
## How was this patch tested?
The test suite is ignored, but I have enabled all these cases offline and it works as expected.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #11463 from yanboliang/spark-13613.