krakatoa: Fail when comet/app misconfigured

**Actual need**:

* Detect when Comet/App are not configured to work properly--i.e. we have krakatoa mempool in app and flood in comet or other configurations which we expect not to work.
* Fail startup when misconfigured.

Original context: im not sure if theres really a way to prevent this, but when mempool type in config.toml is set to flood, and you use the default app in evmd, you cannot send cosmos txs. it fails with sequence errors, as i assume checkTx has incremented sequence, and insert is checking this again.

Start by tracing startup for krakatoa and the default app in evmd, then inspect how config.toml selects the mempool and how Comet/App are configured. Done means incompatible combinations such as krakatoa with flood fail during startup, while supported configurations still allow Cosmos transactions without sequence errors.

Written by the indexing model from the issue text.