Use absl::make_unique_for_overwrite where we will reinitialize the buffer.

PiperOrigin-RevId: 702422246

quiche/balsa/balsa_headers.h

diff --git a/quiche/balsa/balsa_headers.h b/quiche/balsa/balsa_headers.h
index 2e06d1b..ffab219 100644
--- a/quiche/balsa/balsa_headers.h
+++ b/quiche/balsa/balsa_headers.h
@@ -116,7 +116,7 @@
       if (rhs.buffer == nullptr) {
         buffer = nullptr;
       } else {
-        buffer = std::make_unique<char[]>(buffer_size);
+        buffer = absl::make_unique_for_overwrite<char[]>(buffer_size);
         memcpy(buffer.get(), rhs.buffer.get(), rhs.bytes_used());
       }
     }