Testrunner: Temporarily fix long Dex File name issue

Instead of passing long test names, it passes a directory with shorter name.

Bug: 36039166
Test: TMPDIR=/usr/local/google/home/shubhamajmera/aosp/tmp1 \
      TEMP=/usr/local/google/home/shubhamajmera/aosp/tmp1 \
      TMP=/usr/local/google/home/shubhamajmera/aosp/tmp1 \
      ./art/test.py \
      -t test-art-host-run-test-debug-prebuild-interpreter-relocate-npatchoat-ntrace-cms-checkjni-picimage-npictest-ndebuggable-201-built-in-except-detail-messages64 \
      -r

Change-Id: Id361e130301a23cd0c0d10a16cdd0dc48882c22b