Rename subscribeStreamTemporary to subscribeStreamChangesSince

Summary:
# Context

SubscribeStreamTemporary is a function that allows users to recieve notifications whenever there is a change to the edenFS journal. Despite intended to be a temporary function, it's been named as such for about 6 years.

# This Diff
Creates a new function subscribeStreamChangesSince. Move the logic of subscribeStreamTemporary to this new function and have subscribeStreamTemporary call it.

Reviewed By: jdelliot

Differential Revision: D68220555

fbshipit-source-id: de630f60dd66fba77ba3935ca27d95e994acbc7c

eden/fs/service/streamingeden.thrift

@@ -110,25 +110,26 @@ typedef binary EdenStartStatusUpdate
  */
 service StreamingEdenService extends eden.EdenService {
   /**
-   * Request notification about changes to the journal for
-   * the specified mountPoint.
+   * subscribeStreamTemporary is deprecated. Please use streamJournalChanged.
+   */
+  stream<eden.JournalPosition> subscribeStreamTemporary(
+    1: eden.PathString mountPoint,
+  ) (deprecated);
+
+  /**
+   *
+   * Returns a stream of "events" indicating that the Journal has changed.
    *
    * IMPORTANT: Do not use the JournalPosition values in the stream. They are
-   * meaningless. Instead, call getFilesChangedSince or
+   * meaningless. Instead, call changesSinceV2 or
    * getCurrentJournalPosition which will return up-to-date information and
    * unblock future notifications on this subscription. If the subscriber
-   * never calls getFilesChangedSince or getCurrentJournalPosition in
+   * never calls changesSinceV2 or getCurrentJournalPosition in
    * response to a notification on this stream, future notifications may not
    * arrive.
-   *
-   * This is an implementation of the subscribe API using the
-   * new rsocket based streaming thrift protocol.
-   * The name is temporary: we want to make some API changes
-   * but want to start pushing out an implementation now because
-   * we've seen inflated memory usage for the older `subscribe`
-   * method above.
+
    */
-  stream<eden.JournalPosition> subscribeStreamTemporary(
+  stream<eden.JournalPosition> streamJournalChanged(
     1: eden.PathString mountPoint,
   );