Investigate keep calling `eth_getBlockByNumber` at @truffle/artifactor after the upgrade to v4.x

[Muhammad-Altabba]

Investigate in the branch of ConsenSys-archive/truffle#5393

To reproduce

yarn
cd packages/artifactor
yarn test

Logs

Then the tests pass but the execution never ends. And the following keep printing in the console:

...
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
@truffle/artifactor: eth_getBlockByNumber
...

[Muhammad-Altabba]

The following is unrelated, but the code is around: #6328