http2: fix zombie session crash on socket close #3116

Job	Run time
Build slim tarball	1m 51s
aarch64-linux: with shared libraries	35m 39s
x86_64-linux: with shared libraries	47m 43s
aarch64-darwin: with shared libraries	53m 44s
x86_64-darwin: with shared libraries	1h 25m 45s
	3h 44m 42s

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