Reduced online account signatures min and max lifetimes

onlineAccountSignaturesMinLifetime reduced from 720 hours to 12 hours
onlineAccountSignaturesMaxLifetime reduced from 888 hours to 24 hours

These were using up too much space in the database and so it makes sense to trim them more aggressively (assuming testing goes well). We will now stop validating online account signatures after 12 hours, which should be more than enough confirmations, and we will discard them after 24 hours.

Note: this will create some complexity once some of the network is running this code. It could cause out-of-sync nodes on old versions to start treating blocks as invalid from updated peers. It's likely not worth the complexity of a hard fork though, given that almost all nodes will be synced to the chain tip and will therefore be unaffected. And even with a hard fork, we'd still face this problem on out of date nodes.

src/main/resources/blockchain.json

@@ -11,8 +11,8 @@
 	"minAccountLevelToRewardShare": 5,
 	"maxRewardSharesPerMintingAccount": 6,
 	"founderEffectiveMintingLevel": 10,
-	"onlineAccountSignaturesMinLifetime": 2592000000,
-	"onlineAccountSignaturesMaxLifetime": 3196800000,
+	"onlineAccountSignaturesMinLifetime": 43200000,
+	"onlineAccountSignaturesMaxLifetime": 86400000,
 	"rewardsByHeight": [
 		{ "height": 1, "reward": 5.00 },
 		{ "height": 259201, "reward": 4.75 },