script: remove test.bat

The test.bat script has not been maintained for some time and is outdated.  I'm
not sure it has ever seen broad usage.  Remove it.

Should we indeed need it, we'll start with a fresh port of test.bash.

Change-Id: Iefabe24fa0c408552f0012882337bf3f9c006867
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>