[BUG] Reindexing in Zephyr Essentials removes previously indexed data even when "Clean Index" is not selected

[hrachsg]

Steps to Reproduce:

1. Open the Zephyr Essentials toolkit
2. Go to the Indexes tab
3. Run the indexing process without selecting "Clean Index" and ensure documents are indexed
4. Reindex the same collection

Actual Result:
Previously indexed documents are deleted and reindexed again, despite "Clean Index" being unchecked.

2025-10-31_12h25_07.mp4

Expected Result:
When "Clean Index" is not selected, the previously indexed documents should remain intact, and only new data should be added.

[epamLDadayan]

Verified on DEV env