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/execution/worker.go

@@ -9,7 +9,8 @@ import (
 
 	"github.com/riverqueue/river"
 
-	"github.com/zitadel/zitadel/internal/query"
+	"github.com/zitadel/zitadel/internal/crypto"
+	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	exec_repo "github.com/zitadel/zitadel/internal/repository/execution"
 )
 
@@ -18,6 +19,8 @@ type Worker struct {
 
 	config WorkerConfig
 	now    nowFunc
+
+	targetEncAlg crypto.EncryptionAlgorithm
 }
 
 // Timeout implements the Timeout-function of [river.Worker].
@@ -42,7 +45,7 @@ func (w *Worker) Work(ctx context.Context, job *river.Job[*exec_repo.Request]) e
 		return river.JobCancel(fmt.Errorf("unable to unmarshal targets because %w", err))
 	}
 
-	_, err = CallTargets(ctx, targets, exec_repo.ContextInfoFromRequest(job.Args))
+	_, err = CallTargets(ctx, targets, exec_repo.ContextInfoFromRequest(job.Args), w.targetEncAlg)
 	if err != nil {
 		// If there is an error returned from the targets, it means that the execution was interrupted
 		return river.JobCancel(fmt.Errorf("interruption during call of targets because %w", err))
@@ -61,10 +64,12 @@ type WorkerConfig struct {
 
 func NewWorker(
 	config WorkerConfig,
+	targetEncAlg crypto.EncryptionAlgorithm,
 ) *Worker {
 	return &Worker{
-		config: config,
-		now:    time.Now,
+		config:       config,
+		now:          time.Now,
+		targetEncAlg: targetEncAlg,
 	}
 }
 
@@ -77,14 +82,10 @@ func (w *Worker) Register(workers *river.Workers, queues map[string]river.QueueC
 	}
 }
 
-func TargetsFromRequest(e *exec_repo.Request) ([]Target, error) {
-	var execTargets []*query.ExecutionTarget
-	if err := json.Unmarshal(e.TargetsData, &execTargets); err != nil {
+func TargetsFromRequest(e *exec_repo.Request) ([]target_domain.Target, error) {
+	var targets []target_domain.Target
+	if err := json.Unmarshal(e.TargetsData, &targets); err != nil {
 		return nil, err
 	}
-	targets := make([]Target, len(execTargets))
-	for i, target := range execTargets {
-		targets[i] = target
-	}
 	return targets, nil
 }