in_calyptia_fleet: improve configuration reloading. #7962

Job	Run time
run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, gcc)	20m 17s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=On, clang)	19m 16s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, gcc)	18m 10s
run-ubuntu-unit-tests (-DFLB_JEMALLOC=Off, clang)	17m 44s
run-ubuntu-unit-tests (-DFLB_SMALL=On, gcc)	18m 22s
run-ubuntu-unit-tests (-DFLB_SMALL=On, clang)	19m 18s
run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, gcc)	18m 29s
run-ubuntu-unit-tests (-DSANITIZE_ADDRESS=On, clang)	18m 47s
run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, gcc)	18m 32s
run-ubuntu-unit-tests (-DSANITIZE_UNDEFINED=On, clang)	17m 55s
run-ubuntu-unit-tests (-DFLB_COVERAGE=On, gcc)	51m 52s
run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, gcc)	18m 16s
run-ubuntu-unit-tests (-DFLB_SANITIZE_MEMORY=On, clang)	17m 33s
run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, gcc)	17m 53s
run-ubuntu-unit-tests (-DFLB_SANITIZE_THREAD=On, clang)	18m 11s
run-macos-unit-tests (-DFLB_JEMALLOC=Off)	12m 58s
run-macos-unit-tests (-DFLB_SANITIZE_MEMORY=On)	13m 29s
run-macos-unit-tests (-DFLB_SANITIZE_THREAD=On)	13m 8s
Unit tests (matrix)	1s
	5h 50m 11s

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