cardano-testnet: Add tests for lightweight checkpointing configuration

Lightweight checkpointing is introduced in: https://github.com/IntersectMBO/cardano-node/pull/6048

Tests for this feature should be added to `cardano-testnet`.

### Positive scenario

A positive scenario can be tested in the following way:
1. A testnet is started.
2. After few blocks get produced, their hashes are obtained.
3. A new node configuration is created with with enabled checkpointing and just obtained block hashes.
4. The new node is started and joins the newtork.

>[!NOTE]
>This can be done similarly to how it's implemented in in [`KesPeriodInfo` test](https://github.com/IntersectMBO/cardano-node/blob/30a0129716d516241e8758dba9d660ac33354ec7/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/KesPeriodInfo.hs#L261).

#### Expected result
Block hashes are correctly checked and the node starts successfully.

### Negative scenario
However it's possible to implement a negative scenario:

1. Arbitrary block hashes are provided in the configuration.

#### Expected result
1. `cardano-testnet` fails to start due to block hashes checks failure