don't delete grenade logs

we actually want to switch over to summary logs in the gate, so
we need to not delete the logs, as the console will be pretty
empty otherwise:

Change-Id: Ifae56479364ded13fb765ec6158f651888e828ea
bp:grenade-readability

functions.sh

@@ -487,11 +487,6 @@ function cleanup_host {
     sudo cp $BASE/new/devstacklog.txt $NEWLOGTARGET/
     sudo cp $BASE/new/devstack/localrc $NEWLOGTARGET/localrc.txt
 
-    # $BASE/logs is a link to $WORKSPACE (see
-    # devstack-vm-gate-wrap.sh) so we need to clear out a few extra
-    # logs files we don't want to keep
-    sudo rm $BASE/logs/grenade.sh.log.*
-
     # Copy failure files if they exist
     if [ $(ls $BASE/status/stack/*.failure | wc -l) -gt 0 ]; then
         sudo mkdir -p $BASE/logs/status