Increase the default value in order to reduce the time spent in txpool reorg.
When txpool is saturated, txpool reorg can take more than a few seconds to run. This impacts block producer because the producer would need to get the pending txns from txpool, which is blocked by reorg.
* enforce gas configs for all networks
* eth/gasprice: remove else if for log
* docs/cli: update example config
* fix tests
* internal/cli/server: fix tests
* miner: fix tests
