Removing empty test directories

[jeremyf]

These appear to be results of running rails new <app> and are not
used. The applications are tested via RSpec and their corresponding
spec directories.

In removing this, hopefully we reduce the chatter of a what appears to
be a very large code-base.

Related JIRA Ticket or GitHub Issue

See #1651

Motivation and Context

To reduce chatter of files and directories in the code-base.

Related JIRA Ticket or GitHub Issue

See #1651

How Has This Been Tested?

This has not been tested. However there are no references to "test_helper" in the code base.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[lmcglohon]

@jeremyf Thanks for this. We are in the process of improving/refactoring our test infrastructure and this is one of the expected changes.