Interlinks suggestions not dismissed if there's a text at the note end

### Expected
Once the user makes clear they don't want to insert an interlink (e.g. by closing a square bracket), the interlinks suggestions should not be shown. Also, the notes shown in pop-up should depend on the entered text.

### Observed
Under certain conditions, the interlinks pop-up will be shown no matter what the user types in. This is best displayed when inserting the checklists with `- [ ]` in the middle of the note.

The first half of the video shows the correct behaviour, the second half demonstrates the buggy one:

https://user-images.githubusercontent.com/73365754/111455508-8e3c0980-871e-11eb-922b-31fcf195ed64.mov

### Reproduced
0. Have at least two notes
1. Have a note with several lines of text
2. Start a new line in the middle of the note
3. Type in `- [ ]` ~> the interlink pop-up will not be dismissed after `]`.

### Where did you see the bug
- System Make: Parallels Desktop on MBP 16"
- OS: Windows
- OS version: 10 Home 20H2 build 19042.508
- Simplenote app version: 2.8.0-beta2 desktop

Reproduce the issue in the Simplenote desktop app using the listed checklist steps and compare the first and second halves of the video. Trace the interlink suggestions behavior around text entered after a new line, and consider the issue done when closing the square bracket dismisses the popup and its notes reflect the entered text.

Written by the indexing model from the issue text.