Change metric to replication_latency

Metric names do not start with '/'.

Convention wise, the suffix _latency is useful to denote the metric is
tracking how long in wall clock time something took.

The documentation calls this replication latency, so just name the
metric that too.

Change-Id: I35497d42b38b43919394b2013cfee41e2b915ba4
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
index cd97b25..f347652 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
@@ -292,7 +292,7 @@
     long startedAt = TimeUtil.nowMs();
 
     repLog.info("Replication to " + uri + " started...");
-    Timer1.Context context = execTimeMetric.getMetricsTimerContext(config.getName());
+    Timer1.Context context = execTimeMetric.start(config.getName());
     try {
       git = gitManager.openRepository(projectName);
       runImpl();
@@ -361,16 +361,18 @@
   @Singleton
   public static class ExecTimeMetric {
     Timer1<String> execTime;
+
     @Inject
     ExecTimeMetric(MetricMaker metricMaker) {
       execTime = metricMaker.newTimer(
-          "/execution_time",
-          new Description("Successful replication latency")
+          "replication_latency",
+          new Description("Time spent pushing to remote destination.")
             .setCumulative()
-            .setUnit(Description.Units.SECONDS), Field.ofString("destination"));
+            .setUnit(Description.Units.SECONDS),
+          Field.ofString("destination"));
     }
 
-    private Timer1.Context getMetricsTimerContext(String name) {
+    Timer1.Context start(String name) {
       return execTime.start(name);
     }
   }