Copilot: fixup compression timer cleanup

Unfortunately the timer gets deleted to early when the temporary object
that gets copied into the hash gets deleted. Delete the timer only if
the editor widget or client gets destructed.

Amends e6e895d6be

Change-Id: Ifee0dce337e7fc69ffeaeb82901135bd23ea8d81
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/copilot/copilotclient.h

@@ -50,7 +50,6 @@ private:
     QMap<TextEditor::TextEditorWidget *, GetCompletionRequest> m_runningRequests;
     struct ScheduleData
     {
-        ~ScheduleData();
         int cursorPosition = -1;
         QTimer *timer = nullptr;
     };