Use the generic helper for opening file to read in filestream (#29180)

Closes #29113

Author: kvch

CHANGELOG.next.asciidoc

@@ -192,6 +192,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Revert usageDetails api version to 2019-01-01. {pull}28995[28995]
 - Fix in `aws-s3` input regarding provider discovery through endpoint {pull}28963[28963]
 - Fix `threatintel.misp` filters configuration. {issue}27970[27970]
+- Fix opening files on Windows in filestream so open files can be deleted. {issue}29113[29113] {pull}29180[29180] 
 
 *Heartbeat*
 

filebeat/input/filestream/input.go

@@ -29,6 +29,7 @@ import (
 	input "github.com/elastic/beats/v7/filebeat/input/v2"
 	"github.com/elastic/beats/v7/libbeat/common"
 	"github.com/elastic/beats/v7/libbeat/common/cleanup"
+	"github.com/elastic/beats/v7/libbeat/common/file"
 	"github.com/elastic/beats/v7/libbeat/common/match"
 	"github.com/elastic/beats/v7/libbeat/feature"
 	"github.com/elastic/beats/v7/libbeat/logp"
@@ -244,7 +245,7 @@ func (inp *filestream) openFile(log *logp.Logger, path string, offset int64) (*o
 	}
 
 	ok := false
-	f, err := os.OpenFile(path, os.O_RDONLY, os.FileMode(0))
+	f, err := file.ReadOpen(path)
 	if err != nil {
 		return nil, fmt.Errorf("failed opening %s: %s", path, err)
 	}