Clean up reflection-related services keep rules

Prefer using annotations (@UsesReflection + @UsedByReflection) for
various classes that are instantiated via reflection in system server.
The auto-generated keep rules are comparable to the existing ones, but
are easier to maintain and more targeted.

Test: m + diff services.jar for equivalent output
Bug: 210510433
Change-Id: I306b4533f723ee7fafba1de12d7fe446544f8ce7
diff --git a/services/Android.bp b/services/Android.bp
index 7bbb42e..fe35382 100644
--- a/services/Android.bp
+++ b/services/Android.bp
@@ -241,6 +241,7 @@
     libs: [
         "android.hidl.manager-V1.0-java",
         "framework-tethering.stubs.module_lib",
+        "keepanno-annotations",
         "service-art.stubs.system_server",
         "service-permission.stubs.system_server",
         "service-rkp.stubs.system_server",