tmf: Fix SWTBot test on Windows related to short temp path

tmf: Fix SWTBot test on Windows related to short temp path

On Windows, the system property for the temorary path looks like this:
java.io.tmpdir=C:\Users\MARC-A~1\AppData\Local\Temp\

Which is a "short path". When used in comparison with full, canonical
paths, it fails.

Change-Id: I3a90f792791e6983c2eab60d54b1e0694ed98dab
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/60273
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-by: Hudson CI