[Access] Update default grpc message size

[peterargue]

Problem Definition

Currently, the default grpc max message size used by Access and Execution nodes is 20MB:

flow-go/utils/grpcutils/grpc.go

Line 18 in 6ece1c3

const DefaultMaxMsgSize = 1024 * 1024 * 20

The current recommended max size on mainnet is 60MB, and most operators manage this using the cli flag --rpc-max-message-size.

Using a response side size limiter doesn't actually protect the node, since it has already done the work to generate the message. Also, the receive limit on the communication with an upstream Execution node has limited value since ENs are currently trusted. This will change, but before that happens, ANs will stop using gRPC to get data from ENs.

Proposed Solution

Update the default max message size to 1GB. This is much higher that current max data sizes and leaves room for state growth, while also putting a reasonable max on the payload sizes.