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/action/v2/target.go

@@ -9,8 +9,8 @@ import (
 
 	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/command"
-	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore/v1/models"
+	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	"github.com/zitadel/zitadel/pkg/grpc/action/v2"
 )
 
@@ -66,18 +66,18 @@ func (s *Server) DeleteTarget(ctx context.Context, req *connect.Request[action.D
 
 func createTargetToCommand(req *action.CreateTargetRequest) *command.AddTarget {
 	var (
-		targetType       domain.TargetType
+		targetType       target_domain.TargetType
 		interruptOnError bool
 	)
 	switch t := req.GetTargetType().(type) {
 	case *action.CreateTargetRequest_RestWebhook:
-		targetType = domain.TargetTypeWebhook
+		targetType = target_domain.TargetTypeWebhook
 		interruptOnError = t.RestWebhook.InterruptOnError
 	case *action.CreateTargetRequest_RestCall:
-		targetType = domain.TargetTypeCall
+		targetType = target_domain.TargetTypeCall
 		interruptOnError = t.RestCall.InterruptOnError
 	case *action.CreateTargetRequest_RestAsync:
-		targetType = domain.TargetTypeAsync
+		targetType = target_domain.TargetTypeAsync
 	}
 	return &command.AddTarget{
 		Name:             req.GetName(),
@@ -106,13 +106,13 @@ func updateTargetToCommand(req *action.UpdateTargetRequest) *command.ChangeTarge
 	if req.TargetType != nil {
 		switch t := req.GetTargetType().(type) {
 		case *action.UpdateTargetRequest_RestWebhook:
-			target.TargetType = gu.Ptr(domain.TargetTypeWebhook)
+			target.TargetType = gu.Ptr(target_domain.TargetTypeWebhook)
 			target.InterruptOnError = gu.Ptr(t.RestWebhook.InterruptOnError)
 		case *action.UpdateTargetRequest_RestCall:
-			target.TargetType = gu.Ptr(domain.TargetTypeCall)
+			target.TargetType = gu.Ptr(target_domain.TargetTypeCall)
 			target.InterruptOnError = gu.Ptr(t.RestCall.InterruptOnError)
 		case *action.UpdateTargetRequest_RestAsync:
-			target.TargetType = gu.Ptr(domain.TargetTypeAsync)
+			target.TargetType = gu.Ptr(target_domain.TargetTypeAsync)
 			target.InterruptOnError = gu.Ptr(false)
 		}
 	}