perf(milestones): refactor (#8788)

# Which Problems Are Solved

Milestones used existing events from a number of aggregates. OIDC
session is one of them. We noticed in load-tests that the reduction of
the oidc_session.added event into the milestone projection is a costly
business with payload based conditionals. A milestone is reached once,
but even then we remain subscribed to the OIDC events. This requires the
projections.current_states to be updated continuously.


# How the Problems Are Solved

The milestone creation is refactored to use dedicated events instead.
The command side decides when a milestone is reached and creates the
reached event once for each milestone when required.

# Additional Changes

In order to prevent reached milestones being created twice, a migration
script is provided. When the old `projections.milestones` table exist,
the state is read from there and `v2` milestone aggregate events are
created, with the original reached and pushed dates.

# Additional Context

- Closes https://github.com/zitadel/zitadel/issues/8800

internal/command/project_application_saml_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
+	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/eventstore/v1/models"
@@ -76,7 +77,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				),
 			},
 			args: args{
-				ctx:           context.Background(),
+				ctx:           authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp:       &domain.SAMLApp{},
 				resourceOwner: "org1",
 			},
@@ -93,7 +94,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				),
 			},
 			args: args{
-				ctx: context.Background(),
+				ctx: authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp: &domain.SAMLApp{
 					ObjectRoot: models.ObjectRoot{
 						AggregateID: "project1",
@@ -123,7 +124,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				),
 			},
 			args: args{
-				ctx: context.Background(),
+				ctx: authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp: &domain.SAMLApp{
 					ObjectRoot: models.ObjectRoot{
 						AggregateID: "project1",
@@ -154,7 +155,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				idGenerator: id_mock.NewIDGeneratorExpectIDs(t),
 			},
 			args: args{
-				ctx: context.Background(),
+				ctx: authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp: &domain.SAMLApp{
 					ObjectRoot: models.ObjectRoot{
 						AggregateID: "project1",
@@ -201,7 +202,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				idGenerator: id_mock.NewIDGeneratorExpectIDs(t, "app1"),
 			},
 			args: args{
-				ctx: context.Background(),
+				ctx: authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp: &domain.SAMLApp{
 					ObjectRoot: models.ObjectRoot{
 						AggregateID: "project1",
@@ -260,7 +261,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				httpClient:  newTestClient(200, testMetadata),
 			},
 			args: args{
-				ctx: context.Background(),
+				ctx: authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp: &domain.SAMLApp{
 					ObjectRoot: models.ObjectRoot{
 						AggregateID: "project1",
@@ -305,7 +306,7 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 				httpClient:  newTestClient(http.StatusNotFound, nil),
 			},
 			args: args{
-				ctx: context.Background(),
+				ctx: authz.WithInstanceID(context.Background(), "instanceID"),
 				samlApp: &domain.SAMLApp{
 					ObjectRoot: models.ObjectRoot{
 						AggregateID: "project1",
@@ -325,13 +326,13 @@ func TestCommandSide_AddSAMLApplication(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			r := &Commands{
+			c := &Commands{
 				eventstore:  tt.fields.eventstore,
 				idGenerator: tt.fields.idGenerator,
 				httpClient:  tt.fields.httpClient,
 			}
-
-			got, err := r.AddSAMLApplication(tt.args.ctx, tt.args.samlApp, tt.args.resourceOwner)
+			c.setMilestonesCompletedForTest("instanceID")
+			got, err := c.AddSAMLApplication(tt.args.ctx, tt.args.samlApp, tt.args.resourceOwner)
 			if tt.res.err == nil {
 				assert.NoError(t, err)
 			}