Fix large responses with http2 client - extend lifetime with DataSource (#7428)

Co-authored-by: Amaury Chamayou <[email protected]>

Author: eddyashton

src/http/http2_types.h

@@ -44,11 +44,9 @@ namespace http2
   public:
     DataSource() = default;
 
-    DataSource(std::span<const uint8_t> s)
-    {
-      data.assign(s.begin(), s.end());
-      span = s;
-    }
+    DataSource(std::span<const uint8_t> s) :
+      DataSource(std::vector<uint8_t>(s.begin(), s.end()))
+    {}
 
     DataSource(std::vector<uint8_t>&& data_) :
       data(std::move(data_)),