Move all targets away from non-AB

This sets AB_OTA_UPDATER to true by default. OEMs can still
override this variable in their board config if their device
is still on non-AB.

Since some targets(e.g. art target) do not need updates,
we permit empty AB_OTA_PARTITIONS if AB_OTA_UPDATER is true.

This reverts commit 2a3faafdbf

Test: th
Bug: 324360816
Change-Id: Ia9e30983ddc7981659d042a177e9edc8abac6a47

core/Makefile

@@ -6132,12 +6132,6 @@ ifeq ($(AB_OTA_UPDATER),true)
     $(BUILT_TARGET_FILES_DIR): $(TARGET_OUT_OEM)/$(OSRELEASED_DIRECTORY)/product_version
     $(BUILT_TARGET_FILES_DIR): $(TARGET_OUT_ETC)/$(OSRELEASED_DIRECTORY)/system_version
   endif
-
-  # Not checking in board_config.mk, since AB_OTA_PARTITIONS may be updated in Android.mk (e.g. to
-  # additionally include radio or bootloader partitions).
-  ifeq ($(AB_OTA_PARTITIONS),)
-    $(error AB_OTA_PARTITIONS must be defined when using AB_OTA_UPDATER)
-  endif
 endif
 
 ifneq ($(AB_OTA_PARTITIONS),)

core/board_config.mk

@@ -923,7 +923,9 @@ endif
 ###########################################
 # Ensure consistency among TARGET_RECOVERY_UPDATER_LIBS, AB_OTA_UPDATER, and PRODUCT_OTA_FORCE_NON_AB_PACKAGE.
 TARGET_RECOVERY_UPDATER_LIBS ?=
-AB_OTA_UPDATER ?=
+ifeq ($(AB_OTA_UPDATER),)
+AB_OTA_UPDATER := true
+endif
 .KATI_READONLY := TARGET_RECOVERY_UPDATER_LIBS AB_OTA_UPDATER
 
 # Ensure that if PRODUCT_OTA_FORCE_NON_AB_PACKAGE == true, then AB_OTA_UPDATER must be true