aconfig: generate full fakefeatureflagsimpl in prod mode

This change will generate full fakefeatureflagsimpl in prod mode.
FakeFeatureFlagsImp will be the same in test mode and the prod mode.
FeatureFlagsImpl will be all unimplemented in test mode. setFlag,
resetAll are added into the interface FeatureFlags.

The reason to make this change is for project using injection pattern,
the project doesn't have to use test mode to test the flag guarded code.
The project can directly use the FakeFeatureFlagsImpl for testing.

Bug: 294838180
Test: atest AconfigJavaHostTest --host AND atest aconfig.test.java
Change-Id: Ib6d40fd3a9ef872e01594fd4f8d6c4cb10bb173a

tools/aconfig/templates/FakeFeatureFlagsImpl.java.template

@@ -1,27 +1,26 @@
 package {package_name};
-{{ if is_test_mode }}
-import static java.util.stream.Collectors.toMap;
 
 import java.util.HashMap;
 import java.util.Map;
-import java.util.stream.Stream;
 
 public class FakeFeatureFlagsImpl implements FeatureFlags \{
+    public FakeFeatureFlagsImpl() \{
+        resetAll();
+    }
+
 {{ for item in class_elements}}
     @Override
     public boolean {item.method_name}() \{
         return getFlag(Flags.FLAG_{item.flag_name_constant_suffix});
     }
 {{ endfor}}
-    @Override
     public void setFlag(String flagName, boolean value) \{
         if (!this.mFlagMap.containsKey(flagName)) \{
-            throw new IllegalArgumentException("no such flag" + flagName);
+            throw new IllegalArgumentException("no such flag " + flagName);
         }
         this.mFlagMap.put(flagName, value);
     }
 
-    @Override
     public void resetAll() \{
         for (Map.Entry entry : mFlagMap.entrySet()) \{
             entry.setValue(null);
@@ -36,26 +35,11 @@ public class FakeFeatureFlagsImpl implements FeatureFlags \{
         return value;
     }
 
-    private HashMap<String, Boolean> mFlagMap = Stream.of(
+    private Map<String, Boolean> mFlagMap = new HashMap<>(
+        Map.of(
             {{-for item in class_elements}}
-            Flags.FLAG_{item.flag_name_constant_suffix}{{ if not @last }},{{ endif }}
+            Flags.FLAG_{item.flag_name_constant_suffix}, false{{ if not @last }},{{ endif }}
             {{ -endfor }}
         )
-        .collect(
-            HashMap::new,
-            (map, elem) -> map.put(elem, null),
-            HashMap::putAll
-        );
+    );
 }
-{{ else }}
-{#- Generate only stub if in prod mode #}
-public class FakeFeatureFlagsImpl implements FeatureFlags \{
-{{ for item in class_elements}}
-    @Override
-    public boolean {item.method_name}() \{
-        throw new UnsupportedOperationException(
-            "Method is not implemented.");
-    }
-{{ endfor}}
-}
-{{ endif }}