refactor(handler): cache active instances (#9008)

# Which Problems Are Solved

Scheduled handlers use `eventstore.InstanceIDs` to get the all active
instances within a given timeframe. This function scrapes through all
events written within that time frame which can cause heavy load on the
database.

# How the Problems Are Solved

A new query cache `activeInstances` is introduced which caches the ids
of all instances queried by id or host within the configured timeframe.

# Additional Changes

- Changed `default.yaml`
  - Removed `HandleActiveInstances` from custom handler configs
- Added `MaxActiveInstances` to define the maximal amount of cached
instance ids
- fixed start-from-init and start-from-setup to start auth and admin
projections twice
- fixed org cache invalidation to use correct index

# Additional Context

- part of #8999

internal/notification/handlers/queries.go

@@ -31,6 +31,8 @@ type Queries interface {
 	InstanceByID(ctx context.Context, id string) (instance authz.Instance, err error)
 	GetActiveSigningWebKey(ctx context.Context) (*jose.JSONWebKey, error)
 	ActivePrivateSigningKey(ctx context.Context, t time.Time) (keys *query.PrivateKeys, err error)
+
+	ActiveInstances() []string
 }
 
 type NotificationQueries struct {