perf(actionsv2): execution target router (#10564)

# Which Problems Are Solved

The event execution system currently uses a projection handler that
subscribes to and processes all events for all instances. This creates a
high static cost because the system over-fetches event data, handling
many events that are not needed by most instances. This inefficiency is
also reflected in high "rows returned" metrics in the database.

# How the Problems Are Solved

Eliminate the use of a project handler. Instead, events for which
"execution targets" are defined, are directly pushed to the queue by the
eventstore. A Router is populated in the Instance object in the authz
middleware.

- By joining the execution targets to the instance, no additional
queries are needed anymore.
- As part of the instance object, execution targets are now cached as
well.
- Events are queued within the same transaction, giving transactional
guarantees on delivery.
- Uses the "insert many fast` variant of River. Multiple jobs are queued
in a single round-trip to the database.
- Fix compatibility with PostgreSQL 15

# Additional Changes

- The signing key was stored as plain-text in the river job payload in
the DB. This violated our [Secrets
Storage](https://zitadel.com/docs/concepts/architecture/secrets#secrets-storage)
principle. This change removed the field and only uses the encrypted
version of the signing key.
- Fixed the target ordering from descending to ascending.
- Some minor linter warnings on the use of `io.WriteString()`.

# Additional Context

- Introduced in https://github.com/zitadel/zitadel/pull/9249
- Closes https://github.com/zitadel/zitadel/issues/10553
- Closes https://github.com/zitadel/zitadel/issues/9832
- Closes https://github.com/zitadel/zitadel/issues/10372
- Closes https://github.com/zitadel/zitadel/issues/10492

---------

Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>
(cherry picked from commit a9ebc06c77)

internal/api/grpc/server/server.go

@@ -9,11 +9,12 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	healthpb "google.golang.org/grpc/health/grpc_health_v1"
-	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoreflect"
 
 	"github.com/zitadel/zitadel/internal/api/authz"
 	grpc_api "github.com/zitadel/zitadel/internal/api/grpc"
 	"github.com/zitadel/zitadel/internal/api/grpc/server/middleware"
+	"github.com/zitadel/zitadel/internal/crypto"
 	"github.com/zitadel/zitadel/internal/logstore"
 	"github.com/zitadel/zitadel/internal/logstore/record"
 	"github.com/zitadel/zitadel/internal/query"
@@ -60,6 +61,7 @@ func CreateServer(
 	externalDomain string,
 	tlsConfig *tls.Config,
 	accessSvc *logstore.Service[*record.AccessLog],
+	targetEncAlg crypto.EncryptionAlgorithm,
 ) *grpc.Server {
 	metricTypes := []metrics.MetricType{metrics.MetricTypeTotalCount, metrics.MetricTypeRequestCount, metrics.MetricTypeStatusCode}
 	serverOptions := []grpc.ServerOption{
@@ -75,7 +77,7 @@ func CreateServer(
 				middleware.AuthorizationInterceptor(verifier, systemAuthz, authConfig),
 				middleware.TranslationHandler(),
 				middleware.QuotaExhaustedInterceptor(accessSvc, system_pb.SystemService_ServiceDesc.ServiceName),
-				middleware.ExecutionHandler(queries),
+				middleware.ExecutionHandler(targetEncAlg),
 				middleware.ValidationHandler(),
 				middleware.ServiceHandler(),
 				middleware.ActivityInterceptor(),