Linux

fix race condition when cancelling requests after becoming a seed #3267

Job	Run time
build (asio-debugging=on picker-debugging=on)	1s
build (extensions=off logging=off streaming=off super-seeding=off share-mode=off predictive-piece...	1s
pre-commit	1s
build (crypto=gcrypt)	1s
build (mmap-disk-io=off)	1s
check headers	1s
clang-tidy	1s
build dist (ubuntu-20.04)	1s
Fuzzers	1s
build dist (ubuntu-22.04)	1s
Simulations	1s
Tests (address-sanitizer=norecover undefined-sanitizer=norecover crypto=openssl)	1s
Tests (toolset=clang logging=off address-sanitizer=norecover undefined-sanitizer=norecover)	1s
Tests (thread-sanitizer=norecover crypto=openssl release debug-symbols=on cxxflags=-Wno-tsan)	1s
Tests (crypto=gnutls)	1s
Tests (deprecated-functions=off)	1s
	16s

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