apex_sepolicy_tests only if default payload type is ext4

apex_sepolicy_tests relies on `deapexer list -Z`, which is only
available to ext4 type.

Hence, when building with other type, it logs error messages like:

  erofs is not supported for `list`.

Until deapexer supports the feature, let's run the test for ext4.

Bug: 353896817
Test: PRODUCT_DEFAULT_APEX_PAYLOAD_TYPE=erofs m droid
Change-Id: Iff5f3b77136a303976d1aec992d048240c1adf52
diff --git a/core/Makefile b/core/Makefile
index f15edb2..642c5bf 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -5176,6 +5176,8 @@
 # Run apex_sepolicy_tests for all installed APEXes
 
 ifeq (,$(TARGET_BUILD_UNBUNDLED))
+# TODO(b/353896817) apex_sepolicy_tests supports only ext4
+ifeq (ext4,$(PRODUCT_DEFAULT_APEX_PAYLOAD_TYPE))
 intermediate := $(call intermediates-dir-for,PACKAGING,apex_sepolicy_tests)
 apex_dirs := \
   $(TARGET_OUT)/apex/% \
@@ -5215,6 +5217,7 @@
 
 apex_files :=
 intermediate :=
+endif # PRODUCT_DEFAULT_APEX_PAYLOAD_TYPE
 endif # TARGET_BUILD_UNBUNDLED
 
 # -----------------------------------------------------------------