[PLT-5864] Move teammate name display setting to the System Console (#6681)

* move teammate name display setting to the system console

* update all the likes of TeammateNameDisplay names

* fix gofmt error

* rebase and fix conflict

api4/team_test.go

@@ -1422,7 +1422,8 @@ func TestInviteUsersToTeam(t *testing.T) {
 		t.Fatal("should return true")
 	}
 
-	expectedSubject := "[Mattermost] " + th.SystemAdminUser.GetDisplayName() + " invited you to join " + th.BasicTeam.DisplayName + " Team"
+	nameFormat := *utils.Cfg.TeamSettings.TeammateNameDisplay
+	expectedSubject := "[Mattermost] " + th.SystemAdminUser.GetDisplayName(nameFormat) + " invited you to join " + th.BasicTeam.DisplayName + " Team"
 	//Check if the email was send to the rigth email address
 	for _, email := range emailList {
 		var resultsMailbox utils.JSONMessageHeaderInbucket