fix(auth): efficient user session projection (#7187)

* fix(auth): cache users during session projection

* fix(auth.user_sessions): add index for more efficient by user search

cmd/setup/20.go

@@ -0,0 +1,26 @@
+package setup
+
+import (
+	"context"
+	_ "embed"
+
+	"github.com/zitadel/zitadel/internal/database"
+)
+
+var (
+	//go:embed 20.sql
+	addByUserIndexToSession string
+)
+
+type AddByUserIndexToSession struct {
+	dbClient *database.DB
+}
+
+func (mig *AddByUserIndexToSession) Execute(ctx context.Context) error {
+	_, err := mig.dbClient.ExecContext(ctx, addByUserIndexToSession)
+	return err
+}
+
+func (mig *AddByUserIndexToSession) String() string {
+	return "20_add_by_user_index_on_session"
+}