Reland: Map all partitions before calling FinishUpdate for VAB as well

In virtual AB updates, all partitions must be mapped before calling
FinishUpdate. (same requirement as VABC).

Test: recovery sideload
Bug: 393082101
Change-Id: I65f4108703cafaf9d38ca87da18e9bde5b3c0aeb
diff --git a/aosp/update_attempter_android.cc b/aosp/update_attempter_android.cc
index 943c3e4..b46f584 100644
--- a/aosp/update_attempter_android.cc
+++ b/aosp/update_attempter_android.cc
@@ -1363,6 +1363,7 @@
   // previous ApplyPayload() call may have requested powerwash, these
   // settings would be saved in `this->install_plan_`. Inherit that setting.
   install_plan_.powerwash_required = this->install_plan_.powerwash_required;
+  install_plan_.switch_slot_on_reboot = true;
 
   CHECK_NE(install_plan_.source_slot, UINT32_MAX);
   CHECK_NE(install_plan_.target_slot, UINT32_MAX);