test_runner: fix wrong signal exit codes #4000

Job	Run time
Build slim tarball	2m 0s
aarch64-darwin: with shared libraries	23m 50s
x86_64-linux: with shared libraries	25m 33s
aarch64-linux: with shared libraries	21m 24s
x86_64-darwin: with shared libraries	35m 4s
	1h 47m 51s

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