Fix CachePeer.cc:101 "!tcp_up" assertion after cache_peer death #236

Job	Run time
source-maintenance-tests	2m 50s
CodeQL-tests	23m 46s
functionality-tests	18m 59s
build-tests(ubuntu-22.04,gcc,default)	13m 11s
build-tests(ubuntu-22.04,gcc,minimal)	7m 0s
build-tests(ubuntu-22.04,gcc,maximus)	14m 46s
build-tests(ubuntu-22.04,clang,default)	14m 45s
build-tests(ubuntu-22.04,clang,minimal)	8m 47s
build-tests(ubuntu-22.04,clang,maximus)	17m 17s
	2h 1m 21s

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