chore: Enable clang-tidy bugprone-reserved-identifier check (#6456)

.clang-tidy

@@ -34,6 +34,7 @@ Checks: "-*,
   bugprone-pointer-arithmetic-on-polymorphic-object,
   bugprone-posix-return,
   bugprone-redundant-branch-condition,
+  bugprone-reserved-identifier,
   bugprone-return-const-ref-from-parameter,
   bugprone-shared-ptr-array-mismatch,
   bugprone-signal-handler,
@@ -94,7 +95,6 @@ Checks: "-*,
 #
 # bugprone-crtp-constructor-accessibility,
 # bugprone-inc-dec-in-conditions,
-# bugprone-reserved-identifier,
 # bugprone-move-forwarding-reference,
 # bugprone-switch-missing-default-case,
 # bugprone-optional-value-conversion,

src/libxrpl/tx/invariants/InvariantCheck.cpp

@@ -488,8 +488,9 @@ AccountRootsDeletedClean::finalize(
                 return false;
         }
         // Simple types
-        for (auto const& [keyletfunc, _, __] : directAccountKeylets)
+        for (auto const& [keyletfunc, _1, _2] : directAccountKeylets)
         {
+            // TODO: use '_' for both unused variables above once we are in C++26
             if (objectExists(std::invoke(keyletfunc, accountID)) && enforce)
                 return false;
         }