Deprecate STREAM_EVENT_TOPIC

STREAM_EVENT_TOPIC was originally introduced to allow separating the
stream of messages of type EventMessage, so that they could be stamped
by an instance-id and thus underatnd where they originated.

Change I577ceb86 finally removed the need for this distinction, so that
now only the `GERRIT_TOPIC` event should be used.

Annotate the STREAM_EVENT_TOPIC as deprecated to signal that only the
`GERRIT_TOPIC` should be used instead.

Change-Id: I4913da1bdc58268103f02825f9e4cebae76c23c7

src/main/java/com/googlesource/gerrit/plugins/multisite/forwarder/events/EventTopic.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/forwarder/events/EventTopic.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/forwarder/events/EventTopic.java
index 507f067..d8e7607 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/forwarder/events/EventTopic.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/forwarder/events/EventTopic.java
@@ -48,7 +48,10 @@
    * href="https://bugs.chromium.org/p/gerrit/issues/detail?id=14835">Issue 14835</a>.
    *
    * <p>This would allow to *all* events to be streamed to the STREAM_EVENT_TOPICS.
+   *
+   * @deprecated Use {@link #GERRIT_TOPIC} instead.
    */
+  @Deprecated
   STREAM_EVENT_TOPIC("GERRIT.EVENT.STREAM", "streamEvent"),
   GERRIT_TOPIC("gerrit", "gerritEvents");