feat(slr): run duplicate check after finding papers

[InAnYan]

Closes https://github.com/JabRef/jabref-issue-melting-pot/issues/1063

Tried to run a duplicate check after SLR.

Remarks:

• In general, this should not happen and internally SLR must remove (move, merge, treat) duplicate papers.
• I'm not sure that the chosen approach of AutomaticDuplicateRemover is right.

Steps to test

1. Checkout to the latest main branch
2. Run SLR with any query (I used for testing: greek, greeks, ancient greeks)
3. I got around 458 entries

After I run a duplicate finder with clicking "Keep merged", I got 449 entries.

Then:

1. Checkout to this PR
2. Run the same SLR
3. See that you got 449 entries

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• I manually tested my changes in running JabRef (always required)
• [/] I added JUnit tests for changes (if applicable)
• [/] I added screenshots in the PR description (if change is visible to the user)
• [/] I described the change in CHANGELOG.md in a way that is understandable for the average user (if change is visible to the user)
• I checked the user documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request updating file(s) in https://github.com/JabRef/user-documentation/tree/main/en.

[jabref-machine]

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[HoussemNasri]

The way the looping is done now, it is guaranteed that you won't "handle" the same pair of entries twice, so the handledEntries set and the conditions are redundant.