Revert "[MM-8497] Ability to set Do Not Disturb for a specified period of time (#16067)" (#17657)

This reverts commit 77d42568f9.

plugin/api.go

@@ -229,12 +229,6 @@ type API interface {
 	// Minimum server version: 5.2
 	UpdateUserStatus(userID, status string) (*model.Status, *model.AppError)
 
-	// SetUserStatusTimedDND will set a user's status to dnd for given time until the user,
-	// or another integration/plugin, sets it back to online.
-	// @tag User
-	// Minimum server version: 5.35
-	SetUserStatusTimedDND(userId string, endtime int64) (*model.Status, *model.AppError)
-
 	// UpdateUserActive deactivates or reactivates an user.
 	//
 	// @tag User