Save stc temp logs in the stc folder

There was an issue when OCN was set to localhost. As part of Net-Smoke,
the command 'mn -c' is run which removes '/tmp/*.log'. This potentially
caused some tests to fail.

Change-Id: If68c184902b994e1ee38ea775c378ce29cdb891f
diff --git a/tools/test/bin/onos-execute-expect b/tools/test/bin/onos-execute-expect
index 6ad9569..4b9270e 100755
--- a/tools/test/bin/onos-execute-expect
+++ b/tools/test/bin/onos-execute-expect
@@ -13,7 +13,7 @@
 . $ONOS_ROOT/tools/build/envDefaults
 
 
-aux=/tmp/stc-$$.log
+aux=/tmp/stc/stc-$$.log
 trap "rm -f $aux 2>/dev/null" EXIT
 ip=$1
 cmd=""