fix(initrd): Remove the rootfs directly from the testdata directory

The contents are already stored within the tarball so this can just
be simply extracted.  Without this, build environments such as those
provided by GitHub run into "Too many levels of symbolic links"
errors.

Signed-off-by: Alexander Jung <alex@unikraft.io>

initrd/directory_test.go

@@ -10,16 +10,19 @@ import (
 	"os"
 	"testing"
 
+	"kraftkit.sh/archive"
 	"kraftkit.sh/cpio"
 	"kraftkit.sh/initrd"
 )
 
 func TestNewFromDirectory(t *testing.T) {
-	const rootDir = "testdata/rootfs"
+	if err := archive.Unarchive("testdata/rootfs.tar.gz", "testdata/rootfs"); err != nil {
+		t.Fatal("Unarchive:", err)
+	}
 
 	ctx := context.Background()
 
-	ird, err := initrd.NewFromDirectory(ctx, rootDir)
+	ird, err := initrd.NewFromDirectory(ctx, "testdata/rootfs")
 	if err != nil {
 		t.Fatal("NewFromDirectory:", err)
 	}
@@ -32,6 +35,9 @@ func TestNewFromDirectory(t *testing.T) {
 		if err := os.Remove(irdPath); err != nil {
 			t.Fatal("Failed to remove initrd file:", err)
 		}
+		if err := os.RemoveAll("testdata/rootfs"); err != nil {
+			t.Fatal("Failed to remove rootfs directory:", err)
+		}
 	})
 
 	r := cpio.NewReader(openFile(t, irdPath))