Extract PrepareForTestWithJavaSdkLibraryFiles from javaMockFS()

Needed for tests in both java and sdk packages.

Bug: 182638834
Test: m nothing
Change-Id: Ia8c5e7db47d8b63bf8dcf2965b3af60a4d35a9e5
diff --git a/java/java_test.go b/java/java_test.go
index 2ef3f42..356f8f5 100644
--- a/java/java_test.go
+++ b/java/java_test.go
@@ -65,6 +65,7 @@
 		ctx.RegisterPreSingletonType("sdk_versions", sdkPreSingletonFactory)
 	}),
 	javaMockFS().AddToFixture(),
+	PrepareForTestWithJavaSdkLibraryFiles,
 	dexpreopt.PrepareForTestWithDexpreopt,
 )