CORDA-3726: Remove memory leaks when many InProcess nodes started (#6169)

* CORDA-3762: Integration test exposing the problem reported

* CORDA-3726: Additional logging

* CORDA-3726: Prevent thread leaks

* CORDA-3726: New `journalBufferTimeout` parameter

* CORDA-3726: Override `journalBufferTimeout` parameter

* CORDA-3726: Making Detekt happier

* CORDA-3276: Account for extra thread user in MockNetwork

For real node this does not matter as `shutdown` can safely be called multiple times, which is not true for server thread provided by MockNetwork

* CORDA-3276: Do not make SMM shutdown "executor" as it belongs to AbstractNode

* CORDA-3276: Address input from @rick-r3

* CORDA-3276: Fix test after rebase

node-api/src/main/kotlin/net/corda/nodeapi/internal/persistence/CordaPersistence.kt

@@ -289,7 +289,13 @@ class CordaPersistence(
 
     override fun close() {
         // DataSource doesn't implement AutoCloseable so we just have to hope that the implementation does so that we can close it
-        (_dataSource as? AutoCloseable)?.close()
+        val mayBeAutoClosableDataSource = _dataSource as? AutoCloseable
+        if(mayBeAutoClosableDataSource != null) {
+            log.info("Closing $mayBeAutoClosableDataSource")
+            mayBeAutoClosableDataSource.close()
+        } else {
+            log.warn("$_dataSource has not been properly closed")
+        }
     }
 
     @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")