fix(user): unify email validation for registration and settings (#39304)

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

services/forms/user_form_test.go

@@ -46,6 +46,7 @@ func TestRegisterForm_IsDomainAllowed_AllowedEmail(t *testing.T) {
 	}{
 		{"security@gitea.io", true},
 		{"security@gITea.io", true},
+		{"hack%evil.example@gitea.io", false},
 		{"invalid", false},
 		{"seee@example.com", false},
 
@@ -69,6 +70,7 @@ func TestRegisterForm_IsDomainAllowed_BlockedEmail(t *testing.T) {
 	}{
 		{"security@gitea.io", false},
 		{"security@gitea.example", true},
+		{"gitea.io!hack@gitea.example", false},
 		{"invalid", true},
 
 		{"user@my.block", false},