Add a note about when to remove file.exists() check in settings.gradle

Change-Id: I86458d8f2cf3f1d059ab6b81842e7b2a646e359f
Test: None
diff --git a/settings.gradle b/settings.gradle
index 57407b3..ea36d4d 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -395,6 +395,7 @@
         }
         projectReferences[name] = links
     }
+    // Remove file existence checking when https://github.com/gradle/gradle/issues/25531 is fixed.
     if (!file.exists()) {
         // This option is supported so that development/simplify_build_failure.sh can try
         // deleting entire projects at once to identify the cause of a build failure