Switch logging to lifecycle level.

Author: vkryachko

buildSrc/src/main/groovy/com/google/firebase/gradle/plugins/ci/metrics/DrainingBuildListener.java

@@ -30,7 +30,7 @@ class DrainingBuildListener extends BuildAdapter {
   @Override
   public void buildFinished(BuildResult result) {
     try {
-      logger.warn("Draining metrics to Stackdriver.");
+      logger.lifecycle("Draining metrics to Stackdriver.");
       Thread.sleep(sleepDuration);
     } catch (InterruptedException e) {
       // Restore the interrupted status

buildSrc/src/main/groovy/com/google/firebase/gradle/plugins/ci/metrics/MetricsPlugin.java

@@ -23,10 +23,10 @@ public class MetricsPlugin implements Plugin<Project> {
   @Override
   public void apply(Project project) {
     if (!isCollectionEnabled()) {
-      project.getLogger().warn("Metrics collection is disabled.");
+      project.getLogger().lifecycle("Metrics collection is disabled.");
       return;
     }
-    project.getLogger().warn("Metrics collection is enabled.");
+    project.getLogger().lifecycle("Metrics collection is enabled.");
 
     Metrics metrics = new StackdriverMetrics(project.getGradle(), project.getLogger());
 

buildSrc/src/main/groovy/com/google/firebase/gradle/plugins/ci/metrics/StackdriverMetrics.java

@@ -122,10 +122,10 @@ private void ensureStackdriver(Gradle gradle) {
     // make sure we only initialize stackdriver once as gradle daemon is not guaranteed to restart
     // across gradle invocations.
     if (!STACKDRIVER_INITIALIZED.compareAndSet(false, true)) {
-      logger.warn("Stackdriver exporter already initialized.");
+      logger.lifecycle("Stackdriver exporter already initialized.");
       return;
     }
-    logger.warn("Initializing Stackdriver exporter.");
+    logger.lifecycle("Initializing Stackdriver exporter.");
 
     try {
       StackdriverStatsExporter.createAndRegister(