Remove erroneous status reporting (#42435)

This commit removes a redundant status reporting from the Filestream
input. `inp.readFromSource` can only return the error from the
canceler, this error should not be reported to the
manager/Elastic-Agent.

`inp.readFromSource` is called by `filestream.Run`, which is called by
the `startHarvester` function. This function already reports the error
returned by `filestream.Run` and correctly filters out 'context
cancelled' errors.

(cherry picked from commit 1a0a732)

CHANGELOG.next.asciidoc

@@ -176,6 +176,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Fix Netflow Template Sharing configuration handling. {pull}42080[42080]
 - Updated websocket retry error code list to allow more scenarios to be retried which could have been missed previously. {pull}42218[42218]
 - In the `streaming` input, prevent panics on shutdown with a null check and apply a consistent namespace to contextual data in debug logs. {pull}42315[42315]
+- Remove erroneous status reporting to Elastic-Agent from the Filestream input {pull}42435[42435]
 - Fix truncation of bodies in request tracing by limiting bodies to 10% of the maximum file size. {pull}42327[42327]
 
 *Heartbeat*

filebeat/input/filestream/input.go

@@ -35,7 +35,6 @@ import (
 	"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/management/status"
 	"github.com/elastic/beats/v7/libbeat/reader"
 	"github.com/elastic/beats/v7/libbeat/reader/debug"
 	"github.com/elastic/beats/v7/libbeat/reader/parser"
@@ -166,11 +165,9 @@ func (inp *filestream) Run(
 	})
 	defer streamCancel()
 
-	if err := inp.readFromSource(ctx, log, r, fs.newPath, state, publisher, metrics); err != nil {
-		ctx.UpdateStatus(status.Degraded, fmt.Sprintf("error while reading from source: %v", err))
-		return err
-	}
-	return nil
+	// The caller of Run already reports the error and filters out errors that
+	// must not be reported, like 'context cancelled'.
+	return inp.readFromSource(ctx, log, r, fs.newPath, state, publisher, metrics)
 }
 
 func initState(log *logp.Logger, c loginp.Cursor, s fileSource) state {