OPENTHREAD_CONFIG_ANNOUNCE_SENDER_REDUNDANCY_CONSTANT macro

@def OPENTHREAD_CONFIG_ANNOUNCE_SENDER_REDUNDANCY_CONSTANT Specifies the number of MLE Announcement messages that the device must receive within a cycle interval to skip sending the Announcement itself. This is used as the trickle timer redundancy constant in `AnnounceSender`. Applicable only if `AnnounceSender` feature is enabled (see `OPENTHREAD_CONFIG_ANNOUNCE_SENDER_ENABLE`).