fix: walk() should cancel itself upon context cancellation (#15553)

This PR fixes possible leaks that may emanate from not
listening on context cancelation or timeouts.

```
goroutine 60957610 [chan send, 16 minutes]:
github.com/minio/minio/cmd.(*erasureServerPools).Walk.func1.1.1(...)
        github.com/minio/minio/cmd/erasure-server-pool.go:1724 +0x368
github.com/minio/minio/cmd.listPathRaw({0x4a9a740, 0xc0666dffc0},...
        github.com/minio/minio/cmd/metacache-set.go:1022 +0xfc4
github.com/minio/minio/cmd.(*erasureServerPools).Walk.func1.1()
        github.com/minio/minio/cmd/erasure-server-pool.go:1764 +0x528
created by github.com/minio/minio/cmd.(*erasureServerPools).Walk.func1
        github.com/minio/minio/cmd/erasure-server-pool.go:1697 +0x1b7
```

cmd/erasure-single-drive.go

@@ -3007,13 +3007,13 @@ func (es *erasureSingle) Walk(ctx context.Context, bucket, prefix string, result
 		return err
 	}
 
+	vcfg, _ := globalBucketVersioningSys.Get(bucket)
+
 	ctx, cancel := context.WithCancel(ctx)
 	go func() {
 		defer cancel()
 		defer close(results)
 
-		versioned := opts.Versioned || opts.VersionSuspended
-
 		var wg sync.WaitGroup
 		wg.Add(1)
 		go func() {
@@ -3028,15 +3028,17 @@ func (es *erasureSingle) Walk(ctx context.Context, bucket, prefix string, result
 					cancel()
 					return
 				}
-				if opts.WalkAscending {
-					for i := len(fivs.Versions) - 1; i >= 0; i-- {
-						version := fivs.Versions[i]
-						results <- version.ToObjectInfo(bucket, version.Name, versioned)
-					}
-					return
-				}
+
+				versionsSorter(fivs.Versions).reverse()
+
 				for _, version := range fivs.Versions {
-					results <- version.ToObjectInfo(bucket, version.Name, versioned)
+					versioned := vcfg != nil && vcfg.Versioned(version.Name)
+
+					select {
+					case <-ctx.Done():
+						return
+					case results <- version.ToObjectInfo(bucket, version.Name, versioned):
+					}
 				}
 			}
 
@@ -3078,6 +3080,7 @@ func (es *erasureSingle) Walk(ctx context.Context, bucket, prefix string, result
 
 			if err := listPathRaw(ctx, lopts); err != nil {
 				logger.LogIf(ctx, fmt.Errorf("listPathRaw returned %w: opts(%#v)", err, lopts))
+				cancel()
 				return
 			}
 		}()