Add MediaProvider's bootclasspath fragment to its sdk

This subsumes the java_sdk_library in the sdk.

Bug: 188427719
Test: build_mainline_modules.sh
Change-Id: I5f0ec4d2a2413186c5c02ab6d160b49fff32ae22
diff --git a/apex/Android.bp b/apex/Android.bp
index 2668806..b620fe6 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -42,9 +42,7 @@
 
 sdk {
     name: "mediaprovider-module-sdk",
-    java_sdk_libs: [
-        "framework-mediaprovider",
-    ],
+    bootclasspath_fragments: ["com.android.mediaprovider-bootclasspath-fragment"],
 }
 
 // Encapsulate the contributions made by the com.android.mediaprovider to the bootclasspath.