Raise the max grpc message size to a very large value by default (#12072)

* Raise the max grpc message size to a very large value by default

* unused import

---------

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

cmd/flags.go

@@ -3,6 +3,7 @@ package cmd
 
 import (
 	"fmt"
+	"math"
 	"strings"
 
 	"github.com/prysmaticlabs/prysm/v3/config/params"
@@ -215,9 +216,13 @@ var (
 	}
 	// GrpcMaxCallRecvMsgSizeFlag defines the max call message size for GRPC
 	GrpcMaxCallRecvMsgSizeFlag = &cli.IntFlag{
-		Name:  "grpc-max-msg-size",
-		Usage: "Integer to define max recieve message call size (default: 4194304 (for 4MB))",
-		Value: 1 << 22,
+		Name: "grpc-max-msg-size",
+		Usage: "Integer to define max recieve message call size. If serving a public gRPC server, " +
+			"set this to a more reasonable size to avoid resource exhaustion from large messages. " +
+			"Validators with as many as 10000 keys can be run with a max message size of less than " +
+			"50Mb. The default here is set to a very high value for local users. " +
+			"(default: 2147483647 (2Gi)).",
+		Value: math.MaxInt32,
 	}
 	// AcceptTosFlag specifies user acceptance of ToS for non-interactive environments.
 	AcceptTosFlag = &cli.BoolFlag{