engine: fix several file descriptor leaks. #8609

Job	Run time
run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, gcc)	12m 11s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, clang)	12m 8s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, gcc)	11m 31s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, clang)	11m 33s
run-ubuntu-unit-tests (-DFLB_SMALL=On, gcc)	11m 47s
run-ubuntu-unit-tests (-DFLB_SMALL=On, clang)	12m 25s
run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, gcc)	11m 48s
run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, clang)	11m 44s
run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, gcc)	11m 49s
run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, clang)	11m 51s
run-ubuntu-unit-tests (-DFLB_COVERAGE=On, gcc)	42m 56s
run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, gcc)	11m 58s
run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, clang)	11m 34s
run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, gcc)	11m 33s
run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, clang)	11m 46s
run-macos-unit-tests (-DFLB_JEMALLOC=Off)	11m 1s
run-macos-unit-tests (-DFLB_SANITIZE_MEMORY=On)	10m 39s
run-macos-unit-tests (-DFLB_SANITIZE_THREAD=On)	10m 29s
Unit tests (matrix)	1s
	4h 0m 44s

Provide feedback