[clangd] Hide "swap if branch" tweak

[hokein]

Summary

This tweak is more like a demo, and doesn't provide much value in
practice.

[kadircet]

you might want this to be cherry-picked into 11 release

clang-tools-extra/clangd/refactor/tweaks/SwapIfBranches.cpp

 class SwapIfBranches : public Tweak {
 public:
   const char *id() const override final;
 
   bool prepare(const Selection &Inputs) override;
   Expected<Effect> apply(const Selection &Inputs) override;
   std::string title() const override { return "Swap if branches"; }
   Intent intent() const override { return Refactor; }
+  bool hidden() const override { return true; }
 
 private:
   const IfStmt *If = nullptr;
 };
 
 REGISTER_TWEAK(SwapIfBranches)
 
 bool SwapIfBranches::prepare(const Selection &Inputs) {