Change sleepycat.je dependency to a something available in Maven Central

Hi, minor issue and there is some background in this issue: https://github.com/odpi/egeria/issues/1116

It would be helpful (if possible) to bump the `sleepycat.je` dependency to something that's available in Maven Central so downstream projects don't have to add the Oracle repository.

Read the linked background issue 1116, then locate the sleepycat.je dependency declaration in the JanusGraph build files. Identify a compatible dependency available in Maven Central and verify that downstream projects no longer need the Oracle repository.

Written by the indexing model from the issue text.