make writing main test easier (#27270)

This PR removed `unittest.MainTest` the second parameter
`TestOptions.GiteaRoot`. Now it detects the root directory by current
working directory.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/common/errpage_test.go

@@ -9,7 +9,6 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
-	"path/filepath"
 	"testing"
 
 	"code.gitea.io/gitea/models/unittest"
@@ -35,7 +34,5 @@ func TestRenderPanicErrorPage(t *testing.T) {
 }
 
 func TestMain(m *testing.M) {
-	unittest.MainTest(m, &unittest.TestOptions{
-		GiteaRootPath: filepath.Join("..", ".."),
-	})
+	unittest.MainTest(m)
 }