chore: revert small buffer (#5654)

* Revert "perf: use libsmall in libtransmission, pt 3 (#5653)"

This reverts commit 3b03494580.

* Revert "perf: use small in libtransmission (#5650)"

This reverts commit 559f6f0332.

libtransmission/variant-json.cc

@@ -442,7 +442,7 @@ struct JsonWalk
     }
 
     std::deque<ParentState> parents;
-    libtransmission::SmallBuffer<1024 * 16> out;
+    libtransmission::Buffer out;
     bool doIndent;
 };