BEP async mixed mode: If upload mode is set to async, we still block on "fast" upload protocols. We consider local file writes with local uri references to be fast enough for this.

RELNOTES: None
PiperOrigin-RevId: 257235938
diff --git a/src/test/java/com/google/devtools/build/lib/runtime/BuildEventStreamerTest.java b/src/test/java/com/google/devtools/build/lib/runtime/BuildEventStreamerTest.java
index b66080b..0bfb233 100644
--- a/src/test/java/com/google/devtools/build/lib/runtime/BuildEventStreamerTest.java
+++ b/src/test/java/com/google/devtools/build/lib/runtime/BuildEventStreamerTest.java
@@ -140,6 +140,11 @@
     }
 
     @Override
+    public boolean mayBeSlow() {
+      return false;
+    }
+
+    @Override
     public synchronized void sendBuildEvent(BuildEvent event) {
       events.add(event);
       eventsAsProtos.add(