fixes m_assumed_blockchain_size variables values:

This commit was a fix to `m_assumed_blockchain_size` reverted from
3fc2063's 220 to 9d0e528's 200 since work on 9d0e528 was being done in
parallel and ended up reverting `m_assumed_blockchain_size`.

This commits is now a intended to be a bump of
`m_assumed_blockchain_size` for both mainnet and testnet for new
reasonable values.

src/chainparams.cpp

@@ -107,7 +107,7 @@ public:
         pchMessageStart[3] = 0xd9;
         nDefaultPort = 8333;
         nPruneAfterHeight = 100000;
-        m_assumed_blockchain_size = 200;
+        m_assumed_blockchain_size = 240;
         m_assumed_chain_state_size = 3;
 
         genesis = CreateGenesisBlock(1231006505, 2083236893, 0x1d00ffff, 1, 50 * COIN);
@@ -219,7 +219,7 @@ public:
         pchMessageStart[3] = 0x07;
         nDefaultPort = 18333;
         nPruneAfterHeight = 1000;
-        m_assumed_blockchain_size = 20;
+        m_assumed_blockchain_size = 30;
         m_assumed_chain_state_size = 2;
 
         genesis = CreateGenesisBlock(1296688602, 414098458, 0x1d00ffff, 1, 50 * COIN);