Revert "libbinder: Consider VNDK_APEX as vendor stable"

This reverts commit 6b92a6d3830a0f428adf0a2c7ecc53d52c37aa90.

Reason for revert: some targets are broken

Test: m
Bug: 142773030
Change-Id: I6109ecf7a73ea77de1e64981d21329c8c3119bcf
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 9b47f80..6345640 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -505,7 +505,7 @@
     }
 }
 
-#if defined(__ANDROID_APEX_COM_ANDROID_VNDK_CURRENT__) || (defined(__ANDROID_VNDK__) && !defined(__ANDROID_APEX__))
+#if defined(__ANDROID_VNDK__) && !defined(__ANDROID_APEX__)
 constexpr int32_t kHeader = B_PACK_CHARS('V', 'N', 'D', 'R');
 #else
 constexpr int32_t kHeader = B_PACK_CHARS('S', 'Y', 'S', 'T');