eatt: Fix handling indication confirmation timeout

Disconnect EATT channel on which timeout happen instead of ATT fixed
channel.

Bug: 361538527
Bug: 315241296
Test: atest net_test_eatt
Flag: com.android.bluetooth.flags.gatt_disconnect_fix
Change-Id: I3527e5a098782d43b34c192a68e8d20b0a54044b