fix(test): avoid using assert_current_path

Error:
```
Failure:
UserTest#test_can_sign_up [test/system/user_test.rb:47]:
expected to find text "alice@test.com" in
"menu\nMiCarrera\nsearch\ncloud_download\n0 créditos\nA\nBienvenido!
Marcá los cursos y exámenes que aprobaste para ver qué materias podés
cursar.\nLISTO\nBuilt by \nCedarcode". (However, it was found 1 time
including non-visible text.)

bin/rails test test/system/user_test.rb:9
```

Author: nicolastemciuc

test/system/user_test.rb

@@ -41,7 +41,7 @@ class UserTest < ApplicationSystemTestCase
     password_visibility_toggle_test("Confirma tu nueva contraseña")
     click_on "Registrarte"
 
-    assert_current_path root_path
+    assert_text "Bienvenido! Te has registrado correctamente."
 
     click_user_menu
     assert_text "alice@test.com"