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/query/cache.go

@@ -2,7 +2,9 @@ package query
 
 import (
 	"context"
+	"time"
 
+	"github.com/hashicorp/golang-lru/v2/expirable"
 	"github.com/zitadel/logging"
 
 	"github.com/zitadel/zitadel/internal/cache"
@@ -13,9 +15,16 @@ import (
 type Caches struct {
 	instance cache.Cache[instanceIndex, string, *authzInstance]
 	org      cache.Cache[orgIndex, string, *Org]
+
+	activeInstances *expirable.LRU[string, bool]
 }
 
-func startCaches(background context.Context, connectors connector.Connectors) (_ *Caches, err error) {
+type ActiveInstanceConfig struct {
+	MaxEntries int
+	TTL        time.Duration
+}
+
+func startCaches(background context.Context, connectors connector.Connectors, instanceConfig ActiveInstanceConfig) (_ *Caches, err error) {
 	caches := new(Caches)
 	caches.instance, err = connector.StartCache[instanceIndex, string, *authzInstance](background, instanceIndexValues(), cache.PurposeAuthzInstance, connectors.Config.Instance, connectors)
 	if err != nil {
@@ -26,6 +35,8 @@ func startCaches(background context.Context, connectors connector.Connectors) (_
 		return nil, err
 	}
 
+	caches.activeInstances = expirable.NewLRU[string, bool](instanceConfig.MaxEntries, nil, instanceConfig.TTL)
+
 	caches.registerInstanceInvalidation()
 	caches.registerOrgInvalidation()
 	return caches, nil