gowrap fault injection (#7056)

## What changed?
<!-- Describe what has changed in this PR -->

Use [gowrap](https://github.com/hexdigest/gowrap) for generating fault
injection code. Similar to
#7050.

## Why?
<!-- Tell your future self why have you made these changes -->

Less code to maintain.

Before: 238 LOC.

After: 34 line Go Template.

## How did you test it?
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test? Checked in staging env? -->

Existing tests + eyeballing the output.

## Potential risks
<!-- Assuming the worst case, what can be broken when deploying this
change to production? -->

## Documentation
<!-- Have you made sure this change doesn't falsify anything currently
stated in `docs/`? If significant
new behavior is added, have you described that in `docs/`? -->

## Is hotfix candidate?
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be sent to the broader community? (Yes/No) -->