Can't set user setting multiple times

[KN4CK3R]

Regression of #22295

gitea/models/user/setting.go

Lines 151 to 162 in b383652

	// SetUserSetting updates a users' setting for a specific key
	func SetUserSetting(userID int64, key, value string) error {
	if err := validateUserSettingKey(key); err != nil {
	return err
	}
	_, err := cache.GetString(genSettingCacheKey(userID, key), func() (string, error) {
	return value, upsertUserSettingValue(userID, key, value)
	})
	return err
	}

The following code does not work:

SetUserSetting(1, "key", "value") // sets the setting to "value" and adds it to the cache
SetUserSetting(1, "key", "updated value") // does nothing because the cache already has the value and the update is skipped

Setting a value should always invalidate/update the cache and the cache should not prevent the update.

@lunny