[meshcop] avoid unnecessary `RemoveUnsecurePort` (#4821)
[meshcop] avoid unnecessary `RemoveUnsecurePort` (#4821)


librasungirl/openthread,bukepo/openthread,lanyuwen/openthread,srickardti/openthread,bukepo/openthread,librasungirl/openthread,lanyuwen/openthread,abtink/openthread,openthread/openthread,abtink/openthread,lanyuwen/openthread,jwhui/openthread,bukepo/openthread,chshu/openthread,chshu/openthread,srickardti/openthread,bukepo/openthread,abtink/openthread,openthread/openthread,chshu/openthread,srickardti/openthread,lanyuwen/openthread,openthread/openthread,abtink/openthread,jwhui/openthread,chshu/openthread,lanyuwen/openthread,librasungirl/openthread,jwhui/openthread,chshu/openthread,lanyuwen/openthread,chshu/openthread,jwhui/openthread,openthread/openthread,librasungirl/openthread,srickardti/openthread