[HER-1706] PersistLoadProcessor and PersistStoreProcessor can't share same BdbModule

* BdbModule.java
    allow Database instance reuse if BdbConfig is identical instance
* PersistProcessor.java
    convert shared BdbConfig for history db to static constant HISTORY_DB_CONFIG
* PersistOnlineProcessor.java
    use HISTORY_DB_CONFIG, don't close possibly-shared DB on stop()
* PrecedenceLoader.java, PreloadedUriPrecedencePolicy.java
    use HISTORY_DB_CONFIG

commons/src/main/java/org/archive/bdb/BdbModule.java

@@ -329,6 +329,12 @@ Serializable, Closeable {
                     "BdbModule not started; as a Lifecycle bean it must not be an inner bean.");
         }
         if (databases.containsKey(name)) {
+            DatabasePlusConfig dpc = databases.get(name);
+            if(dpc.config == config) {
+                // object-identical configs: OK to share DB
+                return dpc.database;
+            }
+            // unshared config object: might be name collision; error
             throw new IllegalStateException("Database already exists: " +name);
         }