chore: rename megabyte to mebibyte (#3994)

Handles the renaming feedback in
#3904 (comment)

(cherry picked from commit 0ad4d72)

app/benchmarks/benchmark_msg_send_test.go

@@ -307,8 +307,8 @@ func generateMsgSendTransactions(b *testing.B, count int) (*app.App, [][]byte) {
 	return testApp, rawTxs
 }
 
-// megabyte the number of bytes in a megabyte
-const megabyte = 1048576
+// mebibyte the number of bytes in a mebibyte
+const mebibyte = 1048576
 
 // calculateBlockSizeInMb returns the block size in mb given a set
 // of raw transactions.
@@ -317,7 +317,7 @@ func calculateBlockSizeInMb(txs [][]byte) float64 {
 	for _, tx := range txs {
 		numberOfBytes += len(tx)
 	}
-	mb := float64(numberOfBytes) / megabyte
+	mb := float64(numberOfBytes) / mebibyte
 	return mb
 }