Remove option to create boot image based on preloaded classes

From now on, the only supported approach is to use a boot image profile.

Test: make

Change-Id: Ibd8fbd1dd81db0a7b3f3b3e626a70dcc26510224

java/dexpreopt_bootjars_test.go

@@ -62,6 +62,7 @@ func TestDexpreoptBootJars(t *testing.T) {
 	bootArt := dexpreoptBootJars.Output("boot.art")
 
 	expectedInputs := []string{
+		"dex_bootjars/boot.prof",
 		"dex_bootjars_input/foo.jar",
 		"dex_bootjars_input/bar.jar",
 		"dex_bootjars_input/baz.jar",