Use runtime_libs for the dlopen dependency on libartpalette-system.

That will propagate it into requireNativeLibs in the ART APEX manifest.

Test: cat out/soong/.intermediates/art/build/apex/com.android.art/android_common_com.android.art_image/apex_manifest_full.json
  check that requireNativeLibs contains libartpalette-system.so
Bug: 130340935
Change-Id: I09c4030a9c585f10e730b192e7a03c8d87e2d8f3
diff --git a/libartpalette/Android.bp b/libartpalette/Android.bp
index 2f41cf6..66e8bda 100644
--- a/libartpalette/Android.bp
+++ b/libartpalette/Android.bp
@@ -60,7 +60,7 @@
         // and binds the methods in the libartpalette-system library.
         android: {
             // libartpalette.so dlopen()'s libartpalette-system.
-            required: ["libartpalette-system"],
+            runtime_libs: ["libartpalette-system"],
             srcs: ["apex/palette.cc"],
             shared_libs: ["liblog"],
             version_script: "libartpalette.map.txt",