Fix: instant editor cloze bug

[criticalAY]

Purpose / Description

• Blocked by refactor: use field backing property in Instant Editor VM #20501

• When i was switching the increment or no increment, the no increment happens once but then again the cloze is incremented

  • setClozeFieldText always set currentClozeNumber to max + 1 regardless of the current cloze mode.

• There was bug if i tap the switch to increment button twice, and there are no clozes at all then it start with 2, i.e. -> Increment mode -> no increment mode -> increment mode, then starting cloze is 2

  • toggleClozeMode unconditionally called decrementClozeNumber() or incrementClozeNumber() when switching modes.

Fixes

• Fixes [BUG] Switching Cloze Mode Increments Next Cloze #16936

Approach

Add fix and unit test to stop regression

How Has This Been Tested?

Pixel 10

Learning (optional, can help others)

NA

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[ZornHadNoChoice]

Fixes #16936.

[david-allison]

LGTM 👍