Refactor writable warm feature flag to include tiering

Signed-off-by: Neetika Singhal <neetiks@amazon.com>

Author: neetikasinghal

server/src/main/java/org/opensearch/common/settings/FeatureFlagSettings.java

@@ -34,8 +34,8 @@ protected FeatureFlagSettings(
         FeatureFlags.IDENTITY_SETTING,
         FeatureFlags.TELEMETRY_SETTING,
         FeatureFlags.DATETIME_FORMATTER_CACHING_SETTING,
-        FeatureFlags.WRITEABLE_REMOTE_INDEX_SETTING,
-        FeatureFlags.PLUGGABLE_CACHE_SETTING,
-        FeatureFlags.REMOTE_STORE_MIGRATION_EXPERIMENTAL_SETTING
+        FeatureFlags.TIERED_REMOTE_INDEX_SETTING,
+        FeatureFlags.REMOTE_STORE_MIGRATION_EXPERIMENTAL_SETTING,
+        FeatureFlags.PLUGGABLE_CACHE_SETTING
     );
 }

server/src/main/java/org/opensearch/common/util/FeatureFlags.java

@@ -56,10 +56,10 @@ public class FeatureFlags {
     public static final String DATETIME_FORMATTER_CACHING = "opensearch.experimental.optimization.datetime_formatter_caching.enabled";
 
     /**
-     * Gates the functionality of writeable remote index
+     * Gates the functionality of remote index having the capability to move across different tiers
      * Once the feature is ready for release, this feature flag can be removed.
      */
-    public static final String WRITEABLE_REMOTE_INDEX = "opensearch.experimental.feature.writeable_remote_index.enabled";
+    public static final String TIERED_REMOTE_INDEX = "opensearch.experimental.feature.tiered_remote_index.enabled";
 
     /**
      * Gates the functionality of pluggable cache.
@@ -85,11 +85,7 @@ public class FeatureFlags {
         Property.NodeScope
     );
 
-    public static final Setting<Boolean> WRITEABLE_REMOTE_INDEX_SETTING = Setting.boolSetting(
-        WRITEABLE_REMOTE_INDEX,
-        false,
-        Property.NodeScope
-    );
+    public static final Setting<Boolean> TIERED_REMOTE_INDEX_SETTING = Setting.boolSetting(TIERED_REMOTE_INDEX, false, Property.NodeScope);
 
     public static final Setting<Boolean> PLUGGABLE_CACHE_SETTING = Setting.boolSetting(PLUGGABLE_CACHE, false, Property.NodeScope);
 
@@ -99,7 +95,7 @@ public class FeatureFlags {
         IDENTITY_SETTING,
         TELEMETRY_SETTING,
         DATETIME_FORMATTER_CACHING_SETTING,
-        WRITEABLE_REMOTE_INDEX_SETTING,
+        TIERED_REMOTE_INDEX_SETTING,
         PLUGGABLE_CACHE_SETTING
     );
     /**