Improve replacement from ioutil.ReadDir by io.ReadDir

This commit improves the code necessary for replacing the deprecated
`ioutil.ReadDir` call by `io.ReadDir`. A single for loop is used to
iterate over the dirEntries and if there is an error reading the
FileInfo from a DirEntry, we log it and continue to the next
dirEntry. This effectively adds more resilience to the original code
that would not process any segment if the call to `ioutil.ReadDir` had
failed.

libbeat/publisher/queue/diskqueue/segments.go

@@ -22,7 +22,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/fs"
 	"os"
 	"path"
 	"sort"
@@ -170,22 +169,19 @@ func (s bySegmentID) Less(i, j int) bool { return s[i].id < s[j].id }
 // Scan the given path for segment files, and return them in a list
 // ordered by segment id.
 func scanExistingSegments(logger *logp.Logger, pathStr string) ([]*queueSegment, error) {
-	segmentFiles, err := os.ReadDir(pathStr)
+	dirEntries, err := os.ReadDir(pathStr)
 	if err != nil {
 		return nil, fmt.Errorf("could not read queue directory '%s': %w", pathStr, err)
 	}
-	files := make([]fs.FileInfo, 0, len(segmentFiles))
-	for _, entry := range segmentFiles {
-		info, err := entry.Info()
+
+	segments := []*queueSegment{}
+	for _, dirEntry := range dirEntries {
+		file, err := dirEntry.Info()
 		if err != nil {
-			logger.Errorf("could not get info for file '%s': %w. Skipping it", info.Name(), err)
+			logger.Errorf("could not get info for file '%s', skipping. Error: %w", dirEntry.Name(), err)
 			continue
 		}
-		files = append(files, info)
-	}
 
-	segments := []*queueSegment{}
-	for _, file := range files {
 		components := strings.Split(file.Name(), ".")
 		if len(components) == 2 && strings.ToLower(components[1]) == "seg" {
 			// Parse the id as base-10 64-bit unsigned int. We ignore file names that