fix regex for cookie_name to be general snake case

[bazylhorsey]

Proposed change

cookie_name doesn't work as expected. Even when using the one supplied in the full reference config I got config errors. The new pattern is general snakecase

Fixes #14644

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code
• Documentation Update

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• The code has been formatted using Ruff (ruff format frigate)

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