feat: increase default mempool TTLNumBlocks to 12 (#3961)

Motivation in the **Mempool TTL duration** section of
#3959 (comment)

## Description

Modify the default consensus node config for mempools so that:

- TTLNumBlocks from 5 to 12 because 12 six second blocks = 72 seconds
which is comparable to the existing 75 second TTLDuration.
- ~~MaxTxBytes from approx 7.5 MiB to 8 MiB because it's easier to
understand and communicate~~
- ~~MaxTxsBytes from approx 37.6 MiB to 40 MiB because it's easier to
understand and communicate~~

## Testing

`make install && ./scripts/single-node.sh` then cat the config

```toml
version = "v1"
ttl-duration = "1m15s"
ttl-num-blocks = 12
```

app/default_overrides.go

@@ -8,7 +8,6 @@ import (
 	"github.com/celestiaorg/celestia-app/v3/pkg/appconsts"
 	"github.com/celestiaorg/celestia-app/v3/x/mint"
 	minttypes "github.com/celestiaorg/celestia-app/v3/x/mint/types"
-	"github.com/celestiaorg/go-square/v2/share"
 	"github.com/cosmos/cosmos-sdk/codec"
 	serverconfig "github.com/cosmos/cosmos-sdk/server/config"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -259,19 +258,13 @@ func DefaultEvidenceParams() tmproto.EvidenceParams {
 func DefaultConsensusConfig() *tmcfg.Config {
 	cfg := tmcfg.DefaultConfig()
 	// Set broadcast timeout to be 50 seconds in order to avoid timeouts for long block times
-	// TODO: make TimeoutBroadcastTx configurable per https://github.com/celestiaorg/celestia-app/issues/1034
 	cfg.RPC.TimeoutBroadcastTxCommit = 50 * time.Second
 	cfg.RPC.MaxBodyBytes = int64(8388608) // 8 MiB
 
-	cfg.Mempool.TTLNumBlocks = 5
-	cfg.Mempool.TTLDuration = time.Duration(cfg.Mempool.TTLNumBlocks) * appconsts.GoalBlockTime
-	// Given that there is a stateful transaction size check in CheckTx,
-	// We set a loose upper bound on what we expect the transaction to
-	// be based on the upper bound size of the entire block for the given
-	// version. This acts as a first line of DoS protection
-	upperBoundBytes := appconsts.DefaultSquareSizeUpperBound * appconsts.DefaultSquareSizeUpperBound * share.ContinuationSparseShareContentSize
-	cfg.Mempool.MaxTxBytes = upperBoundBytes
-	cfg.Mempool.MaxTxsBytes = int64(upperBoundBytes) * cfg.Mempool.TTLNumBlocks
+	cfg.Mempool.TTLNumBlocks = 12
+	cfg.Mempool.TTLDuration = 75 * time.Second
+	cfg.Mempool.MaxTxBytes = 7_897_088
+	cfg.Mempool.MaxTxsBytes = 39_485_440
 	cfg.Mempool.Version = "v1" // prioritized mempool
 
 	cfg.Consensus.TimeoutPropose = appconsts.TimeoutPropose

app/default_overrides_test.go

@@ -80,11 +80,11 @@ func TestDefaultConsensusConfig(t *testing.T) {
 			Size:                  tmcfg.DefaultMempoolConfig().Size,
 			WalPath:               tmcfg.DefaultMempoolConfig().WalPath,
 
-			// overrides
+			// Overrides
 			MaxTxBytes:   7_897_088,
 			MaxTxsBytes:  39_485_440,
 			TTLDuration:  75 * time.Second,
-			TTLNumBlocks: 5,
+			TTLNumBlocks: 12,
 			Version:      "v1",
 		}
 		assert.Equal(t, want, *got.Mempool)