[netif] remove multicast promiscuous mode configuration #34

Job	Run time
channel-manager-csl	12m 11s
packet-verification-1-1-on-1-3	11m 41s
expects	30m 46s
packet-verification-low-power	9m 1s
thread-1-3-posix	8m 40s
thread-1-3-gcc-m32	10m 8s
thread-1-3-gcc-m64	9m 50s
thread-1-3-clang-10-m32	10m 2s
thread-1-3-clang-10-m64	9m 24s
upload-coverage	0s
	1h 51m 43s

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