Move UsageStore logic to using Grid quota counting instead of RCS emails

[junyuanxue]

What does this change?

This PR moves the logic behind supplier usage status / summary within UsageStore over to using the new quota counting logic, instead of relying on parsing emails from RCS.

• As UsageStore no longer requires fetching from S3, I've made it no longer inheriting from BaseStore. However as it still maintains an in-memory store of over-quota agencies (to be used for the is:under-quota search filter), it still needs a scheduler that refreshes the store on an interval.
• I've changed the exceeded logic from > to >=, as we should start surfacing warning when the quota is full, not just exceeded. This is confirmed by the behaviours below. The wording 'exceeded' is a bit misleading, but as it's used quite extensively, I've refrained from not changing it everywhere.

How should a reviewer test this change?

• I have set the Getty quota in TEST to a very low number in S3, so Getty quota would be full in TEST
• Run the Grid locally with --use-TEST flag
• On launching the Grid you should see some images with the red square with arrow icon indicating they're from a supplier that's hit their quota:

• Click into one of those images, you should see another warning:

• If you search with the is:under-quota filter, the images with the arrow icon should disappear:

• The /quotas page will look like this. Again 4/4 is not exactly 'exceeded', but the alternative is 'quota not full' and I don't think having a 3rd 'quota full' indicator is necessary or particularly useful

Tested? Documented?

• locally by committer
• locally by Guardian reviewer
• on the Guardian's TEST environment
• relevant documentation added or amended (if needed)

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1217597818404838

[github-actions]

Deploy build 15030 of media-service::grid::all to TEST

All deployment options

• Deploy build 15030 of media-service::grid::all to TEST
• Deploy parts of build 15030 to TEST by previewing it first
• What's on TEST right now?

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From guardian/actions-riff-raff.