Fixed unicorn multi-enrollment flow.

Test: Verified that Unicorn SUW flows can now
enroll a face.
Test: Verified normal SUW flow works as expected.

Fixes: 237088482
Fixes: 234663447
Change-Id: I9c4100f61b5e7d40fc9ed67c6918ec7bf31fc30a

src/com/android/settings/biometrics/BiometricEnrollBase.java

@@ -184,7 +184,8 @@ public abstract class BiometricEnrollBase extends InstrumentedActivity {
     @Override
     protected void onStop() {
         super.onStop();
-        if (!isChangingConfigurations() && shouldFinishWhenBackgrounded()) {
+        if (!isChangingConfigurations() && shouldFinishWhenBackgrounded()
+                && !BiometricUtils.isAnyMultiBiometricFlow(this)) {
             setResult(RESULT_TIMEOUT);
             finish();
         }