message: chore: `math/rand` -> `crypto/rand` per Semgrep
diff: @@ -4,9 +4,9 @@ import (
  "bytes"
  "context"
  "crypto/ecdsa"
  + "crypto/rand"
  "io"
  "math/big"
  - "math/rand"
  "github.com/ethereum/go-ethereum/common"
  "github.com/ethereum/go-ethereum/core"
  @@ -248,8 +248,10 @@ func (s *L2Batcher) ActL2BatchSubmitGarbage(t Testing, kind GarbageKind) {
  outputFrame = outputFrame[1:]
  // Replace the output frame with random bytes of length [1, 512]
  case RANDOM:
  - buf := make([]byte, rand.Intn(512)+1)
  - _, err := rand.Read(buf)
  + i, err := rand.Int(rand.Reader, big.NewInt(512))
  + require.NoError(t, err, "error generating random bytes length")
  + buf := make([]byte, i.Int64()+1)
  + _, err = rand.Read(buf)
  require.NoError(t, err, "error generating random bytes")
  outputFrame = buf
  // Remove 4 bytes from the tail end of the output frame
  