Do not wipe data from linked Agreement fields when using "Replace agreement"

Current behaviour is to wipe data from the associated fields when the "Replace agreement" option is used

Required behaviour: when the user selects an item to link from the lookup modal and the look up modal closes, all data which has been entered in associated fields should be be retained.

ERM-542 fixed this behaviour in other similar situations, but the Replace agreement still has old behaviour and needs bringing in line with the others