Remove --engine.num-state-masking-blocks flag from bera-reth and reth_gnosis v2.1.0 compose files

The shared reth template now emits --engine.num-state-masking-blocks=0 which
only exists in paradigmxyz reth v2.6.0+. Two clients reject this flag:
- bera-reth (templates/clients/reth.berachain.yml for berachain mainnet and bepolia)
- reth_gnosis v2.1.0 (templates/clients/reth.gnosis.yml for gnosis mainnet and chiado)

Fix: Override client_command_dbopts_extra in both templates to keep the other
engine flags but exclude --engine.num-state-masking-blocks. Plain paradigmxyz
reth (ethereum etc) continues to emit the flag.

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

berachain/reth/berachain-mainnet-reth-pruned-trace.yml

@@ -98,7 +98,6 @@ services:
       - --engine.always-process-payload-attributes-on-canonical-head
       - --engine.cross-block-cache-size=${BERACHAIN_MAINNET_RETH_STATE_CACHE:-4096}
       - --engine.memory-block-buffer-target=0
-      - --engine.num-state-masking-blocks=0
       - --engine.persistence-threshold=0
       - --full
       - --max-inbound-peers=50