[SettingsProvider] fix userId for System.resetToDefaults

System settings can have different users. When `reset` is called, the
requesting user id should be used.

BUG: 291359166
BUG: 279083734
Test: atest
"CtsProviderTestCases:android.provider.cts.settings.Settings_SystemTest#testResetToDefaults"
--iterations 100

Change-Id: Ib789f0e94f5d12b998efd1bef5dd8574a44de726