[clangd] Enable recovery-ast-type by default.

clang-tools-extra/clangd/ClangdServer.h

struct Options {
     /// (Checks, CheckOptions) are about which clang-tidy checks will be
     /// enabled.
     ClangTidyOptionsBuilder GetClangTidyOptions;
 
     /// If true, turn on the `-frecovery-ast` clang flag.
     bool BuildRecoveryAST = true;
 
     /// If true, turn on the `-frecovery-ast-type` clang flag.
-    bool PreserveRecoveryASTType = false;
+    bool PreserveRecoveryASTType = true;
 
     /// Clangd's workspace root. Relevant for "workspace" operations not bound
     /// to a particular file.
     /// FIXME: If not set, should use the current working directory.
     llvm::Optional<std::string> WorkspaceRoot;
 
     /// The resource directory is used to find internal headers, overriding
     /// defaults and -resource-dir compiler flag).

clang-tools-extra/clangd/tool/ClangdMain.cpp

opt<bool> RecoveryAST{
     cat(Features),
     desc("Preserve expressions in AST for broken code (C++ only)."),
     init(ClangdServer::Options().BuildRecoveryAST),
 };
 
 opt<bool> RecoveryASTType{
     "recovery-ast-type",
     cat(Features),
-    desc("Preserve the type for recovery AST. Note that "
-         "this feature is experimental and may lead to crashes"),
-    init(false),
+    desc("Preserve the type for recovery AST."),
+    init(ClangdServer::Options().PreserveRecoveryASTType),
     Hidden,
 };
 
 opt<bool> FoldingRanges{
     "folding-ranges",
     cat(Features),
     desc("Enable preview of FoldingRanges feature"),
     init(false),