[MM-35039] - Send trial ended email (#17478)

* [MM-35039] - Send trial ended email

* Generations

* Use First name with fallback to username

* Use First name with fallback to username for trial ending email

model/cloud.go

@@ -10,6 +10,7 @@ const (
 	EventTypeFailedPaymentNoCard   = "failed-payment-no-card"
 	EventTypeSendAdminWelcomeEmail = "send-admin-welcome-email"
 	EventTypeTrialWillEnd          = "trial-will-end"
+	EventTypeTrialEnded            = "trial-ended"
 	JoinLimitation                 = "join"
 	InviteLimitation               = "invite"
 )