Revert "Mark FeatureFlags impl member as final"

This reverts commit fca73bcad3a223f6ef7f22edb7cd300583755e72.

Reason for revert: Droidmonitor triggered revert due to build breakage in b/350978649. Will be verifying through ABTD before submission.

Change-Id: I65de159518597289f1e0e3902080f35970842afc
diff --git a/tools/aconfig/aconfig/src/codegen/java.rs b/tools/aconfig/aconfig/src/codegen/java.rs
index 0a52914..9abc892 100644
--- a/tools/aconfig/aconfig/src/codegen/java.rs
+++ b/tools/aconfig/aconfig/src/codegen/java.rs
@@ -473,7 +473,7 @@
                 .unwrap();
         let expect_flags_content = EXPECTED_FLAG_COMMON_CONTENT.to_string()
             + r#"
-            private static final FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
+            private static FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
         }"#;
 
         let expect_featureflagsimpl_content = r#"
@@ -661,7 +661,7 @@
             public static boolean enabledRoExported() {
                 return FEATURE_FLAGS.enabledRoExported();
             }
-            private static final FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
+            private static FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
         }
         "#;
 
@@ -1083,7 +1083,7 @@
             public static boolean enabledRw() {
                 return FEATURE_FLAGS.enabledRw();
             }
-            private static final FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
+            private static FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
         }"#;
 
         let expect_customfeatureflags_content = r#"
diff --git a/tools/aconfig/aconfig/templates/Flags.java.template b/tools/aconfig/aconfig/templates/Flags.java.template
index 2d012f5..e2f70b9 100644
--- a/tools/aconfig/aconfig/templates/Flags.java.template
+++ b/tools/aconfig/aconfig/templates/Flags.java.template
@@ -33,11 +33,8 @@
     public static void unsetFeatureFlags() \{
         Flags.FEATURE_FLAGS = null;
     }
-
-    private static FeatureFlags FEATURE_FLAGS;
-{{ -else }}
-
-    private static final FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
 {{ -endif }}
 
+    private static FeatureFlags FEATURE_FLAGS{{ -if not is_test_mode }} = new FeatureFlagsImpl(){{ -endif- }};
+
 }