Update OmniAuth Helm example for consistency

What does this MR do and why?

This MR sets blockAutoCreatedUsers: false for the Helm OmniAuth example. All other examples (Omnibus, Docker, Self-compiled) use false for this setting - so my change brings consistency for the Helm example.

Side note: this was a point of confusion for my team when rolling out the OmniAuth config with Helm. Because of the conflicting examples some team members were unclear about blockAutoCreatedUsers intended behavior.

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