Revert "aconfig: @hide generated Java code"

This reverts commit 379e09d157.

Reason for revert: Seems to have broken the build. Reverting while investigating.

Change-Id: I37c9a065853ef07b1f1c18355205a2f49dd816c4

tools/aconfig/templates/FakeFeatureFlagsImpl.java.template

@@ -3,7 +3,6 @@ package {package_name};
 import java.util.HashMap;
 import java.util.Map;
 
-/** @hide */
 public class FakeFeatureFlagsImpl implements FeatureFlags \{
     public FakeFeatureFlagsImpl() \{
         resetAll();