Wrong keyword highlighted when searching in a checklist

### Expected
During search, the keyword that we search for should be highlighted.

### Observed
When searching in a checklist, highlighting is broken:

https://user-images.githubusercontent.com/73365754/118772701-b6fe8d80-b88c-11eb-8006-549abcbe93f7.MP4

### Reproduced
1. Create a note with this content:
```
Checklist

- [ ] 2014: (78): Dibya Shankar Mishra(BJD)
- [ ] 2009: (78): Gobardhan Dash (Congress)
- [ ] 2004: (98): Himanshu Shekhar Meher (BJP)
- [ ] 2000: (98): Himanshu Shekhar Meher (BJP)
- [ ] 1995: (98): Bikram Keshari Deo (BJP)
- [ ] 1990: (98): Bikram Keshari Deo (BJP)
- [ ] 1985: (98): Bikram Keshari Deo (Janata Party)
- [ ] 1980: (98): Maheshwar Barad (Congress-I)
- [ ] 1977: (98): Maheshwar Barad (Congress)
- [ ] 1974: (98): Udit Pratap Deo (Swatantra Party)
- [ ] 1971: (92): Trinath Sarab (Swatantra Party)
- [ ] 1967: (92): Maheswar Naik (Swatantra Party)
- [ ] 1961: (37): Maheswar Naik (Ganatantra Parishad)
- [ ] 1951: (20): P. K. Deo (Ganatantra Parishad)
```
2. Search for `bikram`
3. Open the note, navigate through matches

Make|Model|iOS Version|App Version
-|-|-|-
iPhone|XR|14.4.2|4.36.0.0

Reproduce the issue in the iOS app using the checklist content and search for “bikram,” then navigate through the matches as described. Trace the search-result highlighting path for checklist items and verify that the searched keyword, rather than another text fragment, is highlighted when the behavior is fixed.

Written by the indexing model from the issue text.