MM-25006: Fix occurences of unclosed http bodies (#14521)

* MM-25006: Fix occurences of unclosed http bodies

And while here, we also use ioutil.Discard to read the remaining
body instead of reading with ioutil.ReadAll which allocates a separate
byte buffer.

* Fix mistake

* Address review comments

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

model/client4.go

@@ -65,7 +65,7 @@ type Client4 struct {
 
 func closeBody(r *http.Response) {
 	if r.Body != nil {
-		_, _ = ioutil.ReadAll(r.Body)
+		_, _ = io.Copy(ioutil.Discard, r.Body)
 		_ = r.Body.Close()
 	}
 }