A string of senior executives at Davy, the stockbroking and wealth management firm acquired by Bank of Ireland two years ago, have left the business this summer following the expiration of a non-compete clause tying them to the company. The departures have triggered a wave of new hires at the firm, which was put up for sale following a bond trading scandal. The staff reshuffle comes as the board of Davy prepares to appoint a new chief executive, with Gavin Kelly, a senior Bank of Ireland executive, expected to replace the departing Bernard Byrne.  Among the senior members of Davy…