ZTS: zed_start should not fail if zed is already running

zed_start may be called in places where zed is not
typically already running, but this is not a requirement
of the tests.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes #9974

tests/zfs-tests/include/libtest.shlib

@@ -3621,15 +3621,15 @@ function zed_start
 	# Verify the ZED is not already running.
 	pgrep -x zed > /dev/null
 	if (($? == 0)); then
-		log_fail "ZED already running"
-	fi
-
+		log_note "ZED already running"
+	else
 		log_note "Starting ZED"
 		# run ZED in the background and redirect foreground logging
 		# output to $ZED_LOG.
 		log_must truncate -s 0 $ZED_DEBUG_LOG
 		log_must eval "zed -vF -d $ZEDLET_DIR -p $ZEDLET_DIR/zed.pid -P $PATH" \
 		    "-s $ZEDLET_DIR/state 2>$ZED_LOG &"
+	fi
 
 	return 0
 }