Investigate enabling indexer by default

[vladjdk]

• During enhancing compatibility of jsonrpc apis (Draft PR #599), I found many Ethereum rpc queries depends on grpc queries (rpc server → grpc server) for getting comet block data.
• For every header, block, transactions, receipts , etc… queries, rpc server do many encoding/decoding and hash calculation.
• Actually, one of our backend dev said that, when load of rpc queries is high, he observed grpc server capacity was problem.
• So, I think
  1. We need to do benchmark testing for rpc server
  2. And improve performance of rpc
     1. e.g. indexing eth block header
     2. e.g. caching eth block header in memory

[linear]

EVM-305 Investigate enabling indexer by default