nx: Explicitly set as an non-AB target

We will be changing AB to be the default, existing non-AB targets
need to explicitly set AB_OTA_UPDATER to false

Test: th
Change-Id: I86a76296937a6abab1b4495cd66a35144348aafd

BoardConfig.mk

@@ -100,6 +100,9 @@ BOARD_PROPERTY_OVERRIDES_SPLIT_ENABLED := true
 BOARD_VNDK_VERSION                     := current
 PRODUCT_FULL_TREBLE_OVERRIDE           := true
 
+# Updater
+AB_OTA_UPDATER := false
+
 # Verity
 # Only needed for signing
 BOARD_AVB_ENABLE := false