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/queue/queue.go

@@ -2,11 +2,11 @@ package queue
 
 import (
 	"context"
+	"database/sql"
 
-	"github.com/jackc/pgx/v5"
 	"github.com/riverqueue/river"
 	"github.com/riverqueue/river/riverdriver"
-	"github.com/riverqueue/river/riverdriver/riverpgxv5"
+	"github.com/riverqueue/river/riverdriver/riverdatabasesql"
 	"github.com/riverqueue/river/rivertype"
 	"github.com/riverqueue/rivercontrib/otelriver"
 	"github.com/robfig/cron/v3"
@@ -19,8 +19,8 @@ import (
 // Queue abstracts the underlying queuing library
 // For more information see github.com/riverqueue/river
 type Queue struct {
-	driver riverdriver.Driver[pgx.Tx]
-	client *river.Client[pgx.Tx]
+	driver riverdriver.Driver[*sql.Tx]
+	client *river.Client[*sql.Tx]
 
 	config      *river.Config
 	shouldStart bool
@@ -35,7 +35,7 @@ func NewQueue(config *Config) (_ *Queue, err error) {
 		MeterProvider: metrics.GetMetricsProvider(),
 	})}
 	return &Queue{
-		driver: riverpgxv5.New(config.Client.Pool),
+		driver: riverdatabasesql.New(config.Client.DB),
 		config: &river.Config{
 			Workers:    river.NewWorkers(),
 			Queues:     make(map[string]river.QueueConfig),
@@ -111,12 +111,33 @@ func WithQueueName(name string) InsertOpt {
 }
 
 func (q *Queue) Insert(ctx context.Context, args river.JobArgs, opts ...InsertOpt) error {
+	_, err := q.client.Insert(ctx, args, applyInsertOpts(opts))
+	return err
+}
+
+// InsertManyFastTx wraps [river.Client.InsertManyFastTx] to insert all jobs in
+// a single `COPY FROM` execution, within the existing transaction.
+//
+// Opts are applied to each job before sending them to river.
+func (q *Queue) InsertManyFastTx(ctx context.Context, tx *sql.Tx, args []river.JobArgs, opts ...InsertOpt) error {
+	params := make([]river.InsertManyParams, len(args))
+	for i, arg := range args {
+		params[i] = river.InsertManyParams{
+			Args:       arg,
+			InsertOpts: applyInsertOpts(opts),
+		}
+	}
+
+	_, err := q.client.InsertManyFastTx(ctx, tx, params)
+	return err
+}
+
+func applyInsertOpts(opts []InsertOpt) *river.InsertOpts {
 	options := new(river.InsertOpts)
 	for _, opt := range opts {
 		opt(options)
 	}
-	_, err := q.client.Insert(ctx, args, options)
-	return err
+	return options
 }
 
 type Worker interface {