ci: add test optimization reporting for system-tests

[nccatoni]

What does this PR do?

Explicitly passes DD_API_KEY and TEST_OPTIMIZATION_API_KEY secrets (replacing secrets: inherit) to enable Test Optimization reporting for nightly system test runs. Also updates scenarios_groups from appsec to tracer_release.

Motivation

Testing Guidelines

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

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• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
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