storagenode: fix lazyfilewalker failing with SIGPIPE

Lazyfilewalker was failing with SIGPIPE which was quite
misleading. The command was failing because the
the value of the --lower-io-priority flag was assumed
to be an arguement since it was passed as
"--lower-io-priority true" instead "--lower-io-priority=true"

Resolves https://github.com/storj/storj/issues/5900

Change-Id: Icf79fcce76dafee21659d76ee0ce19d8520c8f1d

storagenode/pieces/lazyfilewalker/config.go

@@ -4,7 +4,7 @@
 package lazyfilewalker
 
 import (
-	"strconv"
+	"fmt"
 
 	"storj.io/storj/storagenode/blobstore/filestore"
 )
@@ -37,6 +37,6 @@ func (config *Config) Args() []string {
 		// use the json formatter in the subprocess, so we could read lines and re-log them in the main process
 		// with all the fields intact.
 		"--log.encoding", "json",
-		"--lower-io-priority", strconv.FormatBool(config.LowerIOPriority),
+		fmt.Sprintf("--lower-io-priority=%v", config.LowerIOPriority),
 	}
 }