Adding bootimage_test_harness artifact to droidcore

Currently bootimage_test_harness is only built on a few targets
on release branches. However, we might have a last minute build
breakage on release branches as bootimage_test_harness is not
built on dev branches. Moving it to droidcore so we can have more
completed build coverage on pre-submit/post-submit builds.

Bug: 183865297
Test: `make` then check $OUT
Change-Id: I496609401a9444706726256d2f7b45c6bb69ee94
diff --git a/core/main.mk b/core/main.mk
index 56950ec..3362681 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1573,6 +1573,8 @@
     $(INSTALLED_SUPERIMAGE_EMPTY_TARGET) \
     $(INSTALLED_PRODUCTIMAGE_TARGET) \
     $(INSTALLED_SYSTEMOTHERIMAGE_TARGET) \
+    $(INSTALLED_TEST_HARNESS_RAMDISK_TARGET) \
+    $(INSTALLED_TEST_HARNESS_BOOTIMAGE_TARGET) \
     $(INSTALLED_FILES_FILE) \
     $(INSTALLED_FILES_JSON) \
     $(INSTALLED_FILES_FILE_VENDOR) \
@@ -1750,14 +1752,12 @@
       $(INSTALLED_FILES_JSON_VENDOR_DEBUG_RAMDISK) \
       $(INSTALLED_DEBUG_RAMDISK_TARGET) \
       $(INSTALLED_DEBUG_BOOTIMAGE_TARGET) \
+      $(INSTALLED_TEST_HARNESS_RAMDISK_TARGET) \
+      $(INSTALLED_TEST_HARNESS_BOOTIMAGE_TARGET) \
       $(INSTALLED_VENDOR_DEBUG_BOOTIMAGE_TARGET) \
       $(INSTALLED_VENDOR_RAMDISK_TARGET) \
       $(INSTALLED_VENDOR_DEBUG_RAMDISK_TARGET) \
     )
-    $(call dist-for-goals, bootimage_test_harness, \
-      $(INSTALLED_TEST_HARNESS_RAMDISK_TARGET) \
-      $(INSTALLED_TEST_HARNESS_BOOTIMAGE_TARGET) \
-    )
   endif
 
   ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),true)