Report deletions as succeeded in the fetch-ref-replicated events

The refs deletions were always reported as failing on the stream event
fetch-ref-replicated, because of a mismatch in the ref-spec reported for
deletions.

Prefix the refs deletions with ":", as per git specs[1], for reporting
them correctly in the status map and therefore generating more useful
events on the replication status.

[1] https://git-scm.com/book/en/v2/Git-Internals-The-Refspec under
"Deleting References"

Change-Id: Ibd1b9c97cdc79f4972a65cba8001530bf0a64ab5

src/main/java/com/googlesource/gerrit/plugins/replication/pull/api/DeleteRefCommand.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/pull/api/DeleteRefCommand.java b/src/main/java/com/googlesource/gerrit/plugins/replication/pull/api/DeleteRefCommand.java
index fe558e5..c3f91d6 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/pull/api/DeleteRefCommand.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/pull/api/DeleteRefCommand.java
@@ -73,7 +73,7 @@
                     name.get(),
                     r,
                     sourceLabel);
-                return new RefUpdateState(r, RefUpdate.Result.IO_FAILURE);
+                return new RefUpdateState(":" + r, RefUpdate.Result.IO_FAILURE);
               }
             })
         .toList();
@@ -95,7 +95,7 @@
           taskIdRef,
           refName,
           name);
-      return new RefUpdateState(refName, RefUpdate.Result.NO_CHANGE);
+      return new RefUpdateState(":" + refName, RefUpdate.Result.NO_CHANGE);
     }
 
     repLog.info(
@@ -112,7 +112,7 @@
     Optional<Ref> ref = getRef(name, refName);
     if (!ref.isPresent()) {
       logger.atFine().log("[%s] Ref %s was not found in project %s", taskIdRef, refName, name);
-      return new RefUpdateState(refName, RefUpdate.Result.NO_CHANGE);
+      return new RefUpdateState(":" + refName, RefUpdate.Result.NO_CHANGE);
     }
 
     RefUpdateState deleteResult = deleteRef(name, ref.get());
@@ -149,7 +149,7 @@
       u.setForceUpdate(true);
 
       result = u.delete();
-      return new RefUpdateState(ref.getName(), result);
+      return new RefUpdateState(":" + ref.getName(), result);
     }
   }