Multiple changes:
1. Remove `SetDefaultTarget(ChosenItem);` from `PageLeaveCore`. This was clearing the value every time the page was left.
2. Add event `m_dataGridView_CellValueChanged`. Inside the event, we keep track of which target host/pool was selected
3. Add a check that resets the value set in `m_dataGridView_CellValueChanged` in case the chosen pool is changed.
Signed-off-by: Danilo Del Busso <Danilo.Del.Busso@citrix.com>