OPENDJ-1116 Introduce abstraction for the changelog DB


Removed ReplicationServer.removeDb() + let the exceptions propagate up in ChangelogDB.shutdownDB() and ChangelogDB.removeDB().


ReplicationServer.java:
Removed removeDb(), instead use JEChangelogDB.removeDB().

ChangelogDB.java:
shutdownDB() and removeDB() can now throw ChangelogException.

JEChangelogDB.java:
shutdownCNIndexDB(), shutdownDB() and removeDB() can now throw ChangelogException + ensured code proceed till the end of the methods before throwing the first caught exception.
In removeDB(), called shutdownDB().

*Test[Case].java:
Allowed exceptions to propagate up, this will allow detecting issues in tests suite.