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/eventstore/mock/queue.mock.go

@@ -0,0 +1,62 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: github.com/zitadel/zitadel/internal/eventstore (interfaces: ExecutionQueue)
+//
+// Generated by this command:
+//
+//	mockgen -package mock -destination ./mock/queue.mock.go github.com/zitadel/zitadel/internal/eventstore ExecutionQueue
+//
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	context "context"
+	sql "database/sql"
+	reflect "reflect"
+
+	river "github.com/riverqueue/river"
+	queue "github.com/zitadel/zitadel/internal/queue"
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockExecutionQueue is a mock of ExecutionQueue interface.
+type MockExecutionQueue struct {
+	ctrl     *gomock.Controller
+	recorder *MockExecutionQueueMockRecorder
+}
+
+// MockExecutionQueueMockRecorder is the mock recorder for MockExecutionQueue.
+type MockExecutionQueueMockRecorder struct {
+	mock *MockExecutionQueue
+}
+
+// NewMockExecutionQueue creates a new mock instance.
+func NewMockExecutionQueue(ctrl *gomock.Controller) *MockExecutionQueue {
+	mock := &MockExecutionQueue{ctrl: ctrl}
+	mock.recorder = &MockExecutionQueueMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockExecutionQueue) EXPECT() *MockExecutionQueueMockRecorder {
+	return m.recorder
+}
+
+// InsertManyFastTx mocks base method.
+func (m *MockExecutionQueue) InsertManyFastTx(arg0 context.Context, arg1 *sql.Tx, arg2 []river.JobArgs, arg3 ...queue.InsertOpt) error {
+	m.ctrl.T.Helper()
+	varargs := []any{arg0, arg1, arg2}
+	for _, a := range arg3 {
+		varargs = append(varargs, a)
+	}
+	ret := m.ctrl.Call(m, "InsertManyFastTx", varargs...)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// InsertManyFastTx indicates an expected call of InsertManyFastTx.
+func (mr *MockExecutionQueueMockRecorder) InsertManyFastTx(arg0, arg1, arg2 any, arg3 ...any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	varargs := append([]any{arg0, arg1, arg2}, arg3...)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "InsertManyFastTx", reflect.TypeOf((*MockExecutionQueue)(nil).InsertManyFastTx), varargs...)
+}