Noop minor refactoring of a `apierr/error_override_test.go`

[renaudhartert-db]

Changes

This PR does a minor noop refactoring of apierr/error_override_test.go to better match the style of idiomatic table-tests. In particular, it:

• Inlines the applyOverridesTestCase struct which is replaced with an anonymous struct. There's nothing wrong with that struct per se but seeing it made me think at first that it was doing more than simply defining the table cases.
• Remove the unused name field (was always "") and remove the subtests rather than giving them an arbitrary name (e.g. the index of the test).

Alternatively, we could give meaningful names to the subtests and keep them. Though, what these names should be was not obvious to me.

Tests

The test coverage is the same as before this change.

• [x] make test passing
• [x] make fmt applied
• [x] relevant integration tests applied

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #954 +/- ## ====================================== Coverage ? 7.03% ====================================== Files ? 282 Lines ? 65398 Branches ? 0 ====================================== Hits ? 4602 Misses ? 60487 Partials ? 309 ```

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