Remove IME from the client repository when sending EXIT command

Remove IME from the client repository when sending EXIT command

Even after sending EXIT command to the currently selected IME,
the IME may not get destroyed right away due to its termination
logic, meaning the client repository still holds the IME info
until the socket connection is completely closed.
This would cause an unexpected result if the user first selects
IME A and then IME B, and IME A again.
After the last "IME A selected" event, if the socket connection to
previous IME A gets closed, panel would think the current IME
(that was launched due to the last selection for IME A) needs to be
restarted, so it tries launching new IME A instance.
To prevent this, we will going to remove IME info from client
repository right after we send the EXIT request command.

Change-Id: I28cdcf7796028d59cc6929c182abd64868309053