cloudsql_maintenance rule miss non compliant instances

[BrunoReboul]

the current REGO rules looks for instance with a defined hour settings, but instance with no defined maintenance window appers now as;

                "maintenanceWindow": {
                    "day": 0,
                    "hour": 0,
                    "kind": "sql#maintenanceWindow"
                },

So day is a better setting to control instead of hour as dqys index is"

• 0 maintenance window not defined
• 1 Monday
• 2 Tuesday
• 3 Wednesday
• 4 Thursday
• 5 Friday
• 6 Saturday
• 7 Sunday

While hours index is:

• 0 0am to 1am UTC
• up to 23