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/mock/queries.mock.go

@@ -46,6 +46,20 @@ func (m *MockQueries) EXPECT() *MockQueriesMockRecorder {
 	return m.recorder
 }
 
+// ActiveInstances mocks base method.
+func (m *MockQueries) ActiveInstances() []string {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "ActiveInstances")
+	ret0, _ := ret[0].([]string)
+	return ret0
+}
+
+// ActiveInstances indicates an expected call of ActiveInstances.
+func (mr *MockQueriesMockRecorder) ActiveInstances() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "ActiveInstances", reflect.TypeOf((*MockQueries)(nil).ActiveInstances))
+}
+
 // ActiveLabelPolicyByOrg mocks base method.
 func (m *MockQueries) ActiveLabelPolicyByOrg(ctx context.Context, orgID string, withOwnerRemoved bool) (*query.LabelPolicy, error) {
 	m.ctrl.T.Helper()