More job metrics, less tables

[jessarcher]

• Removes the QueueSizes recorder and table. This approach took snapshots every 15 seconds and only captured the current number of pending and failed jobs for connection and queue.
• Updates the Jobs recorder to capture the first time the job began processing, the time it failed, and the time it was processed. This now gives us the stats for the Queues and the SlowJobs cards. It also allows us to display additional stats, such as the number of processed jobs in a period.
• Updates the Queues card to display graphs for the current period, instead of a table with only the current values:

[driesvints]

@jessarcher the first image with the light background could do with a slightly darker background for the metric box so it's a bit different than the white background of the card.

[jessarcher]

@jessarcher the first image with the light background could do with a slightly darker background for the metric box so it's a bit different than the white background of the card.

Good call - I've updated it (and the screenshot above)