Lucene index growing without bound

[cbeach47]

Describe the bug
Indexed portlets in lucene are being duplicated in the index. This causes unnecessary growth of the raw search results. Currently, there's only a check in the code to remove duplicates before exposing to the user.

To Reproduce
Steps to reproduce the behavior:

1. PortalInit a fresh clone of uP-start
2. Import several portlets that all would be returned in a search (for example, all contain 'course' in the name)
3. Start uP and wait 3 minutes for the indexing to complete.
4. Note the number of documents in the lucene index (search for name:course in Luke)
5. Wait another 3 minutes for the indexing task to run again.
6. Reopen the index in luke. Note the number of documents in the lucene index has now grown.

Expected behavior
The Lucene indexed documents should not grow unless content is added/changed.

Platform:

• uPortal Version: 5.6.1
• OS: Ubuntu
• Browser Firefox

[cbeach47]

Also happens in uP 5.7.1