Improve DB IDO HA failover behaviour

Improve DB IDO HA failover behaviour

- Decrease Object Authority updates to 10s (was 30s)
- Decrease failover timeout to 30s (was 60s)
- Decrease cold startup (after (re)start) with no OA updates to 30s (was 60s)
- Immediately connect on Resume()
- Fix query priority which got broken with #6970
- Add more logging when a failover is in progress

```
[2019-03-29 16:13:53 +0100] information/IdoMysqlConnection: Last update by endpoint 'master1' was 8.33246s ago (< failover timeout of 30s). Retrying.

[2019-03-29 16:14:23 +0100] information/IdoMysqlConnection: Last update by endpoint 'master1' was 38.3288s ago. Taking over 'ido-mysql' in HA zone 'master'.
```

- Add more logging for reconnect and disconnect handling
- Add 'last_failover' attribute to IDO*Connection objects

refs #6970