[clangd] Remove redundant findRefs calls. NFC.

Summary:
Remove redundant `findRefs` calls.

Reviewers: sammccall, kadircet

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82714

Author: lh123

clang-tools-extra/clangd/XRefs.cpp

@@ -993,7 +993,6 @@ std::vector<DocumentHighlight> findDocumentHighlights(ParsedAST &AST,
           DeclRelation::TemplatePattern | DeclRelation::Alias;
       auto Decls = targetDecl(N->ASTNode, Relations);
       if (!Decls.empty()) {
-        auto Refs = findRefs({Decls.begin(), Decls.end()}, AST);
         // FIXME: we may get multiple DocumentHighlights with the same location
         // and different kinds, deduplicate them.
         for (const auto &Ref : findRefs({Decls.begin(), Decls.end()}, AST))