[Minor] Remove the warning of blocks generating too fast - v2.2.0-60 Echelon

[mawenpeng]

This version decreased block generating interval. When running anon-cli getinfo, it shows warnings that too many blocks generated than expected in last 4 hours. We may need to change the calculation mechanism to remove such warnings.

$ anon-cli getinfo { "version": 2020060, "protocolversion": 180008, "walletversion": 60000, "balance": 0.00000000, "blocks": 79458, "timeoffset": 0, "connections": 10, "proxy": "", "difficulty": 730150.4406224537, "testnet": false, "keypoololdest": 1573919873, "keypoolsize": 101, "paytxfee": 0.00000000, "relayfee": 0.00001000, "errors": "WARNING: abnormally high number of blocks generated, 100 blocks received in the last 4 hours (24 expected)" }

Steps to reproduce:

• Run anond v2.2.0-60 Echelon and sync to the highest block.
• Run anon-cli getinfo .