fix(fields): add index to improve search by aggregate (#8267)

# Which Problems Are Solved

During performance testing of the `eventstore.fields` table we found
some long running queries which searched for the aggregate id.

# How the Problems Are Solved

A new index was added to the `eventstore.fields`-table called
`f_aggregate_object_type_idx`.

# Additional Changes

None

# Additional Context

- Table was added in https://github.com/zitadel/zitadel/pull/8191
- Part of https://github.com/zitadel/zitadel/issues/7639

(cherry picked from commit 23bebc7e30)

cmd/setup/31.go

@@ -0,0 +1,27 @@
+package setup
+
+import (
+	"context"
+	_ "embed"
+
+	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/eventstore"
+)
+
+var (
+	//go:embed 31.sql
+	addAggregateIndexToFields string
+)
+
+type AddAggregateIndexToFields struct {
+	dbClient *database.DB
+}
+
+func (mig *AddAggregateIndexToFields) Execute(ctx context.Context, _ eventstore.Event) error {
+	_, err := mig.dbClient.ExecContext(ctx, addAggregateIndexToFields)
+	return err
+}
+
+func (mig *AddAggregateIndexToFields) String() string {
+	return "31_add_aggregate_index_to_fields"
+}