x/tariff/keeper: hoist out sdk.ZeroInt() into a global variable to avoid needless allocations

[odeke-em]

If we examine a bunch of loops like

noble/x/tariff/keeper/allocation.go

Lines 11 to 15 in d809e7e

	for _, coin := range feesCollectedInt {
	if coin.Amount.GT(sdk.ZeroInt()) {
	foundAmountGreaterThanZero = true
	break
	}

noble/x/tariff/keeper/allocation.go

Lines 27 to 32 in d809e7e

	for _, coin := range feesToDistribute {
	truncated, _ := coin.TruncateDecimal()
	if truncated.Amount.GT(sdk.ZeroInt()) {
	foundAmountGreaterThanZero = true
	break
	}

noble/x/tariff/keeper/allocation.go

Lines 44 to 48 in d809e7e

	for _, s := range entityShare {
	truncated, _ := s.TruncateDecimal()
	if truncated.Amount.GT(sdk.ZeroInt()) {
	coins = append(coins, truncated)
	}

noble/x/tariff/keeper/keeper.go

Line 84 in d809e7e

if feeInt.Equal(sdk.ZeroInt()) {

we see that for every coin we invoke sdk.ZeroInt() and that has a real cost added trying to find the first non-zero coin

Suggestion

We can remove these unnecessary costs entirely by creating a global variable then using it in the comparisons to remove those unnecessary high costs and allocations

var zeroInt = sdk.ZeroInt()

func (k Keeper) AllocateTokens(ctx sdk.Context) {
	...
	foundAmountGreaterThanZero := false
	for _, coin := range feesCollectedInt {
		if coin.Amount.GT(zeroInt) {
			foundAmountGreaterThanZero = true
			break
		}
	}