Explore the possibility of closing appender logs when not used

[thilinamb]

During load testing with larger number of entities per node (~520,000), following error can be observed.

sustain.synopsis.dht.store.StorageException: Error initializing journal log. Dir: /s/lattice-80/a/nobackup/granules/thilinab/sustain-logs/cfm8f_metadata.slog
	at sustain.synopsis.dht.journal.Logger.initAppenders(Logger.java:39)
	at sustain.synopsis.dht.journal.Logger.append(Logger.java:45)
	at sustain.synopsis.dht.store.entity.EntityStoreJournal.startSession(EntityStoreJournal.java:148)
	at sustain.synopsis.dht.store.entity.EntityStore.startSession(EntityStore.java:108)
	at sustain.synopsis.dht.store.entity.EntityStore.store(EntityStore.java:121)
	at sustain.synopsis.dht.store.node.NodeStore.store(NodeStore.java:215)
	at sustain.synopsis.dht.store.node.NodeStore.store(NodeStore.java:141)
	at sustain.synopsis.dht.IngestionRequestDispatcher.lambda$getNodeMappingCompletableFuture$0(IngestionRequestDispatcher.java:29)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.FileNotFoundException: /s/lattice-80/a/nobackup/granules/thilinab/sustain-logs/cfm8f_metadata.slog (Too many open files)
	at java.io.FileOutputStream.open0(Native Method)
	at java.io.FileOutputStream.open(FileOutputStream.java:270)
	at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
	at java.io.FileOutputStream.<init>(FileOutputStream.java:133)
	at sustain.synopsis.dht.journal.Logger.initAppenders(Logger.java:32)
	... 11 more