Failure at startup when enabling layered txpool before initial sync done

[fab-10]

Description

Enabling the layered txpool #5290 before the initial sync is done, causes Besu to fail to start with this error

2023-06-23 12:48:11.172+02:00 | main | INFO  | TransactionPoolFactory | Using layered transaction pool
class org.hyperledger.besu.ethereum.mainnet.feemarket.LegacyFeeMarket cannot be cast to class org.hyperledger.besu.ethereum.mainnet.feemarket.BaseFeeMarket (org.hyperledger.besu.ethereum.mainnet.feemarket.LegacyFeeMarket and org.hyperledger.besu.ethereum.mainnet.feemarket.BaseFeeMarket are in unnamed module of loader 'app')

Workaround until the fix is ready, is to enabled the layered txpool only after Besu is synced.

Steps to Reproduce (Bug)

Start Besu with --Xlayered-tx-pool=true

Frequency: [What percentage of the time does it occur?]
Only when syncing

Versions (Add all that apply)

• Software version: >= 23.4.1