Remove setActiveUser together with frameworks/base (see 12/n)

setActiveUser is removed from the @hide API surface and is no longer
necessary. The framework ensures that the correct user is set without
an explicit call, since userId is sent as a parameter to each of the
methods already.

Bug: 157790417
Test: See testing from frameworks/base change (12/n) from the same
      gerrit topic
Change-Id: Id88b818ed0bb1f75f18ac8e9ba7aff2a9b80b319

src/com/android/settings/password/ConfirmDeviceCredentialActivity.java

@@ -351,8 +351,6 @@ public class ConfirmDeviceCredentialActivity extends FragmentActivity {
     }
 
     private void showBiometricPrompt(PromptInfo promptInfo) {
-        mBiometricManager.setActiveUser(mUserId);
-
         mBiometricFragment = (BiometricFragment) getSupportFragmentManager()
                 .findFragmentByTag(TAG_BIOMETRIC_FRAGMENT);
         boolean newFragment = false;