Change Issue deadline to 24hours

> This is a low risk change but high impact gain to be had on reducing friction to issuance. Please consider for fast track.

Brief

To aid with issuance of IBTC, we should consider changing the issue deadline parameter back to original 24 Hours value originally intended.

Detail

Currently the block time hovers around 12-13s, however assuming an optimistic 12 seconds:

14,400 blocks x 12second per block = 172800 Seconds
172800 seconds = 48 Hours

Therefore:

7200 block delay = 24 Hours

Explanation

During some of Kintsugi's days there was high BTC network congestion. The deadline is split into issue and redeem, however so only griefing collateral is at stake (which is capped currently at writing at 0.5%) so there is no risk that decreasing this deadline will jeopardise interlay vaults.

The benefit to be had from decreasing this deadline though, is that any: unintended, malevolent or trollish issue requests will be rejected by the system quicker and allow for the corresponding vault collateral to be unsealed in half the time.