[clangd] Tweak the no-index error message for rename, NFC.

Summary: The current error message doesn't fit well for cross-file rename.

Reviewers: ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70809

clang-tools-extra/clangd/refactor/Rename.cpp

@@ -186,7 +186,7 @@ llvm::Error makeError(ReasonToReject Reason) {
     case ReasonToReject::NoSymbolFound:
       return "there is no symbol at the given location";
     case ReasonToReject::NoIndexProvided:
-      return "symbol may be used in other files (no index available)";
+      return "no index provided";
     case ReasonToReject::UsedOutsideFile:
       return "the symbol is used outside main file";
     case ReasonToReject::NonIndexable: