Fix ExtServices tests

- Switch the tests from Android.mk to Android.bp. The app itself
cannot move over yet because it uses syntax not supported by bp
- Instrument the test package instead of the package udner test
- Also fix an actual error in a test

Test: this
Change-Id: I0af081ab25630e4e911d4d9cbb60a87b2f75be90
Fixes: 123572762
diff --git a/packages/ExtServices/Android.bp b/packages/ExtServices/Android.bp
new file mode 100644
index 0000000..77972fe
--- /dev/null
+++ b/packages/ExtServices/Android.bp
@@ -0,0 +1,11 @@
+android_library {
+    name: "ExtServices-core",
+     srcs: [
+         "src/**/*.java",
+     ],
+     resource_dirs: [
+         "res",
+     ],
+
+     manifest: "AndroidManifest.xml",
+}
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