ZOOKEEPER-4306: Avoid `CloseSessionTxns` larger than `jute.maxbuffer`, `branch-3.9` #2269

Job	Run time
mvn (full-build-jdk8, 8, -Pfull-build apache-rat:check verify -DskipTests spotbugs:check checksty...	2m 22s
mvn (full-build-jdk11, 11, -Pfull-build apache-rat:check verify -DskipTests spotbugs:check checks...	2m 33s
mvn (full-build-java-tests, 11, -Pfull-build verify -Dsurefire-forkcount=1 -DskipCppUnit -Dsurefi...	1h 5m 58s
mvn (full-build-cppunit-tests, 11, -Pfull-build verify -Dtest=_ -DfailIfNoTests=false)	11m 22s
	1h 22m 15s

Provide feedback