in_kubernetes_events: fix k8s events end of stream deadlock #9714

Job	Run time
run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, gcc)	13m 36s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, clang)	13m 37s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, gcc)	12m 57s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, clang)	12m 42s
run-ubuntu-unit-tests (-DFLB_SMALL=On, gcc)	12m 54s
run-ubuntu-unit-tests (-DFLB_SMALL=On, clang)	13m 33s
run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, gcc)	13m 10s
run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, clang)	12m 53s
run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, gcc)	13m 11s
run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, clang)	13m 5s
run-ubuntu-unit-tests (-DFLB_COVERAGE=On, gcc)	46m 7s
run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, gcc)	12m 52s
run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, clang)	13m 14s
run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, gcc)	12m 57s
run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, clang)	12m 52s
run-macos-unit-tests	0s
Unit tests (matrix)	1s
	3h 49m 41s

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