mcproxy: fast leave fixed
Fast leave issue is fixed for mcproxy. Added a check to not to send igmp group specific queries in case fast leave is enabled.
Tested on cdrouter: http://cdr1.ctfw.iopsys.eu/results/20230615114109
Tested scripts: IPTV_IGMP_4-12-1-20_2397.py and IPTV_IGMP_4-12-1-24_2401.py on TAPIR.