cros_run_unit_tests: stop installing into $PATH

Since chromite's cros_run_unit_tests is in $PATH and works, stop
installing this stub as that just messes people up.  We keep the
old path around for people running `./cros_run_unit_tests`, but
that doesn't apply to `cros_run_unit_tests`.

BUG=chromium:486263
TEST=precq passes

Change-Id: I8dfc40087e04df2472532e50fc99e6bb4a89cdb6
Reviewed-on: https://chromium-review.googlesource.com/274601
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/Makefile b/Makefile
index 73c541f..154d141 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,6 @@
 	mkdir -p "${DESTDIR}/usr/lib/crostestutils"
 	mkdir -p "${DESTDIR}/usr/share/crostestutils"
 	install -m 0644 lib/constants.py "${DESTDIR}/usr/lib/crostestutils"
-	install -m 0755 cros_run_unit_tests "${DESTDIR}/usr/bin"
 	install -m 0755 cros_run_bvt "${DESTDIR}/usr/bin"
 	install -m 0755 run_remote_tests.sh ${DESTDIR}/usr/bin
 	install -m 0755 test_that ${DESTDIR}/usr/bin