Increase the intensity of main-cron daily tests

[lmatz]

By looking at https://github.com/risingwavelabs/risingwave/blob/main/ci/workflows/main-cron.yml,
the timeout is usually set to 40 minutes at most, with some others being set to 5, 15, or 30 minutes.

We can run many more and/or longer in the main-cron daily test:

• use more random seeds for deterministic Madsim tests
• use different random seeds every day
• more node killing/recovery
• ......

With the intention to bring the effective time for each test, if it can, to 3 hours.
If we can afford the cost, increase it to an even larger number in the future.