fix: ensure Check evaluates deterministically on the eval boundary case

[jon-whit]

Description

This PR ensures Check evaluations are deterministic when two concurrent evaluation paths are on the boundary of evaluating a path that would encounter the AuthorizationModelTooComplexError case and another concurrent path that would yield an {allowed: true} outcome.

References

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

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.07 🎉

Comparison is base (6b70b06) 78.05% compared to head (e3a07ba) 78.12%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #732      +/-   ##
==========================================
+ Coverage   78.05%   78.12%   +0.07%     
==========================================
  Files          59       59              
  Lines        7088     7092       +4     
==========================================
+ Hits         5532     5540       +8     
+ Misses       1269     1267       -2     
+ Partials      287      285       -2     

Impacted Files	Coverage Δ
internal/graph/check.go	91.71% <100.00%> (+1.40%)	⬆️

... and 1 file with indirect coverage changes

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