Treat splash partition as non-A/B in update_engine

This commit modifies update_engine to ignore A/B partition handling
for the splash partition, enabling splash.img updates via OTAs.

Issue: FP3-A13#311
Change-Id: I5b04a5fd0282cb3f020911bbbb8a97f3238fdf6a
diff --git a/aosp/dynamic_partition_control_android.cc b/aosp/dynamic_partition_control_android.cc
index 334ccdc..295af7f 100644
--- a/aosp/dynamic_partition_control_android.cc
+++ b/aosp/dynamic_partition_control_android.cc
@@ -1130,8 +1130,7 @@
   const base::FilePath device_dir(device_dir_str);
   // When VABC is enabled, we can't get device path for dynamic partitions in
   // target slot.
-  const auto& partition_name_suffix =
-      partition_name + SlotSuffixForSlotNumber(slot);
+  const auto& partition_name_suffix = partition_name + (partition_name == "splash" ? "" : SlotSuffixForSlotNumber(slot));
   if (UpdateUsesSnapshotCompression() && slot != current_slot &&
       IsDynamicPartition(partition_name, slot)) {
     return {