Add more comprehensive test for Grid Search to Flow tests

Description

recently reported this issue:

```
water.api.FSIOException: FS IO Failure:
accessed path : file:/grid-5a8fd9bf-fc42-4185-906e-a62857234a23 caused by: /grid-5a8fd9bf-fc42-4185-906e-a62857234a23 (Permission denied)
at water.persist.PersistFS.create(PersistFS.java:137)
at hex.grid.Grid.exportBinary(Grid.java:507)
at hex.grid.GridSearch.gridSearch(GridSearch.java:253)
at hex.grid.GridSearch.access$000(GridSearch.java:71)
at hex.grid.GridSearch$1.compute2(GridSearch.java:139)
at water.H2O$H2OCountedCompleter.compute(H2O.java:1417)
at jsr166y.CountedCompleter.exec(CountedCompleter.java:468)
at jsr166y.ForkJoinTask.doExec(ForkJoinTask.java:263)
at jsr166y.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:974)
at jsr166y.ForkJoinPool.runWorker(ForkJoinPool.java:1477)
at jsr166y.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:104)
Caused by: java.io.FileNotFoundException: /grid-5a8fd9bf-fc42-4185-906e-a62857234a23 (Permission denied)
at java.io.FileOutputStream.open0(Native Method)
```

while running Grid Search from Flow

This was not caught by our testing framework => we need to extend the test suite to cover this particular case as well.

Status

Assignee

Zuzana Olajcov√°

Fix versions

Reporter

Michal Kurka

Support ticket URL

None

Labels

None

Affected Spark version

None

Customer Request Type

None

Task progress

None

CustomerVisible

No

Priority

Major
Configure