move fix version of YARN-4287 from 2.8.0 to 2.7.3

hadoop-yarn-project/CHANGES.txt

@@ -508,8 +508,6 @@ Release 2.8.0 - UNRELEASED
 
     YARN-4310. FairScheduler: Log skipping reservation messages at DEBUG level (asuresh)
 
-    YARN-4287. Capacity Scheduler: Rack Locality improvement (Nathan Roberts via wangda)
-
     YARN-4279. Mark ApplicationId and ApplicationAttemptId static methods as @Public,
     @Unstable. (stevel)
 
@@ -1017,6 +1015,8 @@ Release 2.7.3 - UNRELEASED
 
   IMPROVEMENTS
 
+    YARN-4287. Capacity Scheduler: Rack Locality improvement (Nathan Roberts via wangda)
+
   OPTIMIZATIONS
 
   BUG FIXES