address comments

Signed-off-by: Kaituo Li <kaituo@amazon.com>

build-tools/coverage.gradle

@@ -10,7 +10,7 @@ jacoco {
 }
 
 /**
- * This code sets up coverage reporting manually for the k-NN plugin tests. This is complicated because:
+ * This code sets up coverage reporting manually for the AD plugin tests. This is complicated because:
  *  1. The OS integTest Task doesn't implement Gradle's JavaForkOptions so we have to manually start the jacoco agent with the test JVM
  *  2. The cluster nodes are stopped using 'kill -9' which means jacoco can't dump it's execution output to a file on VM shutdown
  *  3. The Java Security Manager prevents JMX from writing execution output to the file.

src/main/java/org/opensearch/forecast/settings/ForecastEnabledSetting.java

@@ -27,9 +27,6 @@ public class ForecastEnabledSetting extends DynamicNumericSetting {
      */
     public static final String FORECAST_ENABLED = "plugins.forecast.enabled";
 
-    // TODO: remove the field when releasing forecasting
-    public static boolean enabled = false;
-
     public static final Map<String, Setting<?>> settings = unmodifiableMap(new HashMap<String, Setting<?>>() {
         {
             /**
@@ -56,10 +53,6 @@ public static synchronized ForecastEnabledSetting getInstance() {
      * @return whether forecasting is enabled.
      */
     public static boolean isForecastEnabled() {
-        // keep the dynamic setting in main branch to enable writing tests.
-        // will make it hardcoded false in the 2.x branch.
         return ForecastEnabledSetting.getInstance().getSettingValue(ForecastEnabledSetting.FORECAST_ENABLED);
-        // TODO: enable forecasting before released
-        // return enabled;
     }
 }