refactor: Enable more clang-tidy readability checks (#6595)

Co-authored-by: Sergey Kuznetsov <kuzzz99@gmail.com>

src/test/app/LedgerMaster_test.cpp

@@ -8,7 +8,7 @@ namespace test {
 
 class LedgerMaster_test : public beast::unit_test::suite
 {
-    std::unique_ptr<Config>
+    static std::unique_ptr<Config>
     makeNetworkConfig(uint32_t networkID)
     {
         using namespace jtx;