fix: remove action feature flag and include execution (#9727)

# Which Problems Are Solved

Actions v2 is not a feature flag anymore, include functionality on
executions is not used and json tags of proto messages are handled
incorrectly.

# How the Problems Are Solved

- Remove actions from the feature flags on system and instance level
- Remove include type on executions, only in the API, later maybe in the
handling logic as well
- Use protojson in request and response handling of actions v2

# Additional Changes

- Correct integration tests for request and response handling
- Use json.RawMessage for events, so that the event payload is not
base64 encoded
- Added separate context for async webhook calls, that executions are
not cancelled when called async

# Additional Context

Related to #9759 
Closes #9710

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/api/grpc/action/v2beta/integration_test/target_test.go

@@ -19,7 +19,6 @@ import (
 
 func TestServer_CreateTarget(t *testing.T) {
 	instance := integration.NewInstance(CTX)
-	ensureFeatureEnabled(t, instance)
 	isolatedIAMOwnerCTX := instance.WithAuthorization(CTX, integration.UserTypeIAMOwner)
 	type want struct {
 		id           bool
@@ -244,7 +243,6 @@ func assertCreateTargetResponse(t *testing.T, creationDate, changeDate time.Time
 
 func TestServer_UpdateTarget(t *testing.T) {
 	instance := integration.NewInstance(CTX)
-	ensureFeatureEnabled(t, instance)
 	isolatedIAMOwnerCTX := instance.WithAuthorization(CTX, integration.UserTypeIAMOwner)
 	type args struct {
 		ctx context.Context
@@ -463,7 +461,6 @@ func assertUpdateTargetResponse(t *testing.T, creationDate, changeDate time.Time
 
 func TestServer_DeleteTarget(t *testing.T) {
 	instance := integration.NewInstance(CTX)
-	ensureFeatureEnabled(t, instance)
 	iamOwnerCtx := instance.WithAuthorization(CTX, integration.UserTypeIAMOwner)
 	tests := []struct {
 		name             string