Fix early return after populating currentFiles from diffSummary

Without an early return, `currentFilePaths()` would fall through after
populating `currentFiles` from the already-loaded diff summary,
unnecessarily fetching the change and current patch set and then
re-computing the file list via `DiffOperations`. The diff summary path
was clearly intended as a fast exit, but the missing `return` meant it
was silently ignored every time.

Release-Notes: skip
Change-Id: I1e7feeb4c62476d606173677cc826634d3c11dee

java/com/google/gerrit/server/query/change/ChangeData.java

diff --git a/java/com/google/gerrit/server/query/change/ChangeData.java b/java/com/google/gerrit/server/query/change/ChangeData.java
index 49b1165..6ac66bf 100644
--- a/java/com/google/gerrit/server/query/change/ChangeData.java
+++ b/java/com/google/gerrit/server/query/change/ChangeData.java
@@ -622,6 +622,7 @@
       // If the diff summary was already loaded get the path from it.
       if (diffSummary != null) {
         currentFiles = diffSummary.get().getPaths();
+        return currentFiles;
       }
 
       Change c = change();