fix: remove private key in config file

Author: JuArce

config-files/config-proof-aggregator-mock.yaml

@@ -1,6 +1,5 @@
 aligned_service_manager_address: "0x851356ae760d987E095750cCeb3bC6014560891C"
 proof_aggregation_service_address: "0xB0D4afd8879eD9F52b28595d31B441D079B2Ca07"
-private_key: "0x2a871d0798f97d79848a013d4936a73bf4cc922c825d33c1cf7073dff6d409c6"
 eth_rpc_url: "http://localhost:8545"
 eth_ws_url: "ws://localhost:8545"
 max_proofs_in_queue: 1000