Move product_packages.txt to soong

Needed for soong-only builds.

Bug: 383892968
Test: Presubmits
Change-Id: I07642eae89dc4f72476216a70f85efb07856d460
diff --git a/core/Makefile b/core/Makefile
index 3ba931c..a951715 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -885,11 +885,6 @@
 $(call declare-1p-target,$(SOONG_TO_CONVERT),build)
 $(call dist-for-goals,droidcore-unbundled,$(SOONG_TO_CONVERT))
 
-$(PRODUCT_OUT)/product_packages.txt:
-	@rm -f $@
-	echo "" > $@
-	$(foreach x,$(PRODUCT_PACKAGES),echo $(x) >> $@$(newline))
-
 MK2BP_CATALOG_SCRIPT := build/make/tools/mk2bp_catalog.py
 PRODUCT_PACKAGES_TXT := $(PRODUCT_OUT)/product_packages.txt
 MK2BP_REMAINING_HTML := $(PRODUCT_OUT)/mk2bp_remaining.html