tests: Add context cancelation (#15374)

A huge number of goroutines would build up from various monitors

When creating test filesystems provide a context so they can shut down when no longer needed.

cmd/fs-v1.go

@@ -118,8 +118,7 @@ func initMetaVolumeFS(fsPath, fsUUID string) error {
 }
 
 // NewFSObjectLayer - initialize new fs object layer.
-func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
-	ctx := GlobalContext
+func NewFSObjectLayer(ctx context.Context, fsPath string) (ObjectLayer, error) {
 	if fsPath == "" {
 		return nil, errInvalidArgument
 	}