Reset CI minutes notifications for new monthly tracking

What does this MR do?

Related to #290961 (closed)

The main goal of this MR is to reset new monthly data about CI minutes notifications sent to the customer. We already reset CI minutes consumption for the legacy tracking (done in namespace_statistics.shared_runners_seconds). In this MR we are resetting the data for the new tracking that is done in ci_namespace_monthly_usages where we track:

• the consumption, in amount_used
• last notification sent out, in notification_level

We reset this data:

1. any time the CI minutes limits change for a given namespace:
   • when CI monthly minutes change (namespaces.shared_runners_minutes_limit) due to the customer changing plan
   • when CI additional minutes change (namespaces.extra_shared_runners_minutes_limit) due to the customer purchasing more CI minutes
2. any time the CI minutes consumption is reset by admins
   • I've also renamed ClearNamespaceSharedRunnersMinutesService to Ci::Minutes::ResetUsageService in order to be a service object under Ci::Minutes:: namespace. This service is called when an admin resets the CI minutes consumption to 0.

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How to setup and validate locally (strongly suggested)

Does this MR meet the acceptance criteria?

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