Fix bug reading from socket when dropping a cluster on a remote database...

Fix a bug when dropping a cluster on a remote database. To reproduce the bug, with the console (on a database called mydb) :
```
bin\console.bat "connect remote:localhost/mydb admin admin;create cluster ca PHYSICAL default default append;create cluster cb PHYSICAL default default append;create cluster cc PHYSICAL default default append"
bin\console.bat "connect remote:localhost/mydb admin admin;drop cluster cb"
```
The second command blocks. This also happens when importing an old database.

The bug was caused by the call to updateRecord in dropCluster before closing the response (with endResponse)