Ignore cycle errors in union reducer

[willvedd]

Description

The union() function is a reducer that accepts any number of handlers and makes a check decision based on the combination of all those reducers. It is how the union operator is implemented in models with the or syntax.

Generally, if one or more handler within the reducer is truthy, the whole evaluation returns true. If all handlers are falsey, then the union reducer will return false. Errors generally override any truthy or falsey resolution. If one handler errors for any reason, even if other handlers are truthy, the reducer will return that error.

However, the ErrCycleDetected is not an error that should be considered a critical error. It should be considered the same as a falsey result because it signals that a resolution branch was exhausted without any truthy result. Ignoring this error within the union reducer will result in a more correct and fault-tolerant check resolution.

**Note: ** Similar changes may need to be made in the intersection and exclusion reducers. This PR is meant to serve as a starting point for those conversations.

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[jon-whit]

@willvedd I know it's verbose and ugly, but can we explicit use _ for spaces, because Go replaces spaces with _ in the test output. It's easy to search/find tests by name if their names matches the exact Go output. This is why we use _ in our test names explicitly elsewhere.