Switch run_tests.sh to use subunit-trace

Since colorizer was removed in https://review.openstack.org/#/c/163591
run_tests.sh needs to be updated to not use it as well.

closes-bug: #1522526

Change-Id: I10e5e724345e6e1881a7129fa3b2d46e8ff3ad93
diff --git a/run_tests.sh b/run_tests.sh
index 9a158e4..908056f 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -90,9 +90,9 @@
   fi
 
   if [ $serial -eq 1 ]; then
-      ${wrapper} testr run --subunit $testrargs | ${wrapper} subunit-2to1 | ${wrapper} tools/colorizer.py
+      ${wrapper} testr run --subunit $testrargs | ${wrapper} subunit-trace -n -f
   else
-      ${wrapper} testr run --parallel --subunit $testrargs | ${wrapper} subunit-2to1 | ${wrapper} tools/colorizer.py
+      ${wrapper} testr run --parallel --subunit $testrargs | ${wrapper} subunit-trace -n -f
   fi
 }