docs: add javadoc on leader election exit flag #6073

Job	Run time
check_format_and_unit_tests	1m 24s
build / Special integration tests (25)	1m 59s
build / Special integration tests (21)	2m 22s
build / Special integration tests (17)	2m 6s
build / httpclient-tests (jdk) / Integration tests (25, 1.32.0, jdk)	26m 12s
build / httpclient-tests (vertx) / Integration tests (25, 1.32.0, vertx)	25m 52s
build / integration_tests (21, 1.32.4) / Integration tests (21, 1.32.4, vertx)	24m 51s
build / integration_tests (25, 1.30.12) / Integration tests (25, 1.30.12, vertx)	24m 33s
build / integration_tests (17, 1.32.4) / Integration tests (17, 1.32.4, vertx)	25m 19s
build / httpclient-tests (jetty) / Integration tests (25, 1.32.0, jetty)	26m 37s
build / integration_tests (21, 1.31.8) / Integration tests (21, 1.31.8, vertx)	26m 18s
build / integration_tests (17, 1.30.12) / Integration tests (17, 1.30.12, vertx)	24m 17s
build / integration_tests (17, 1.33.1) / Integration tests (17, 1.33.1, vertx)	26m 4s
build / integration_tests (25, 1.32.4) / Integration tests (25, 1.32.4, vertx)	25m 20s
build / integration_tests (21, 1.33.1) / Integration tests (21, 1.33.1, vertx)	25m 47s
build / integration_tests (21, 1.30.12) / Integration tests (21, 1.30.12, vertx)	24m 41s
build / integration_tests (25, 1.33.1) / Integration tests (25, 1.33.1, vertx)	26m 32s
build / integration_tests (17, 1.31.8) / Integration tests (17, 1.31.8, vertx)	26m 32s
build / integration_tests (25, 1.31.8) / Integration tests (25, 1.31.8, vertx)	25m 48s
	6h 32m 34s

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