Pack the mainline modules test keys into the otatools.zip

Bug: 256565230
Test: make dist, check otatools.zip
Change-Id: I7c386ee8f8e3ec6f3d5c767504e23cb1f1bacad2
diff --git a/core/Makefile b/core/Makefile
index 6f9a500..a3b79a9 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -5045,6 +5045,10 @@
   $(sort $(shell find build/make/target/product/security -type f -name "*.x509.pem" -o \
       -name "*.pk8"))
 
+INTERNAL_OTATOOLS_PACKAGE_FILES += \
+  $(sort $(shell find packages/modules -type f -name "*.x509.pem" -o -name "*.pk8" -o -name \
+      "key.pem"))
+
 ifneq (,$(wildcard device))
 INTERNAL_OTATOOLS_PACKAGE_FILES += \
   $(sort $(shell find device $(wildcard vendor) -type f -name "*.pk8" -o -name "verifiedboot*" -o \