Fix CI Flakes

Currently, both [unit](https://github.com/cosmos/evm/actions/runs/18413974998/job/52473099121) and [system tests ](https://github.com/cosmos/evm/actions/runs/18413975010/job/52473099230)are flaking on the \~18th minute of their 20-minute run.

The unit tests are failing due to race conditions in the txpool, and the system tests fail due to flaky replacements.

The latter specify that the tx could not be found, but the root cause is probably something like the feemarket increasing the gas past the point for which it is set. To see the actual cause of the flakes, we should add a debug log every time [we broadcast a transaction to read the actual response](https://github.com/cosmos/evm-internal/blob/ef7a8f386ba34112774b306d926f6bc0c3d1e968/tests/systemtests/clients/cosmosclient.go#L108).

Success for this task means:

- [ ] Unit tests no longer have flaky race conditions
- [x] System tests no longer have flaky transaction submissions
- [x] We have debug logs in the system tests whenever transactions are submitted, such that they will be reflected during failures.

Start by reproducing the linked unit-test and system-test failures, then inspect the txpool race and flaky transaction replacements. Review tests/systemtests/clients/cosmosclient.go around the transaction broadcast at line 108 and use the existing debug logs to identify submission responses. Done means unit-test race flakes are resolved and transaction failures are diagnosable from CI logs.

Written by the indexing model from the issue text.