mcproxy: handle mcproxy max group count
- added handling to exclude multicast address 224.0.0.106 allsnooper address from max group count
pipeline execution of test PASS, https://dev.iopsys.eu/devops/ctfw-launcher/-/jobs/437407
pipeline execution of test PASS, https://dev.iopsys.eu/devops/ctfw-launcher/-/jobs/437407