Split mysqld--help-notwin test into debug and release tests.

Summary:
This wasn't firing any errors, because the test requires perfschema(?).

But, if we build with perfschema, this test can't work, since we use
different build options for release and debug, and thus have different
command-line parameters for each.

This splits this test so it can actually work, when it's actually run.

Test Plan: When perfschema is enabled, these tests pass.

Reviewers: jtolmer

Reviewed By: jtolmer