Closes #6015

Why is this the best possible solution? Were any other approaches considered?

We had at least two issues with this case when a repeatable group was wrapped with a regular one:

1. The fact that the regular group in the hierarchy was visible as a removable one. I've described it in Crash in the Nested repeats for audit form while removing an empty inner repeat #6015 (comment)
2. A wrong path was displayed in the hierarchy when navigating up.

I think I've fixed both issues using the appropriate form index.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

The pr is not big but I find it risky. We need to test the hierarchy view with nested groups (repeatable and regular ones) to make sure they are displayed in the correct way. @dbemke @srujner @WKobus please be creative and create your own forms ideally with multiple levels of nested groups.

Do we need any specific form for testing your changes? If so, please attach one.

The form I've attached in this comment: #6015 (comment)

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No.

Before submitting this PR, please make sure you have:

• added or modified tests for any new or changed behavior
• run ./gradlew connectedAndroidTest (or ./gradlew testLab) and confirmed all checks still pass
• added a comment above any new strings describing it for translators
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines