Use large timeout to ensure no flaky banzai specs

What does this MR do and why?

We occasionally have flaky specs due to using Timeout.timeout to test the handling of malicious inputs for Banzai filters. In order to ensure this does not happen, use a large timeout value. This ensures that a test won't suddenly become exceedingly long, but it doesn't really protect against a spec going from 1 second to 15 seconds.

Ideally we find a better way/metric for these types of tests.

See #475039 (comment 2024746601)

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