fix: correctly unmarshal login names and metadata in user repository (#11775)

## Problem description

When calling `repository.UserRepository().Get(...)` the following error
got returned caused by scanning.

`Scan error: scanning: doing scan: scanFn: scany: scan row into struct
fields: sql: Scan error on column index 7, name "metadata": unsupported
Scan, storing driver.Value type []uint8 into type *[]*domain.Metadata`

## How the problem got solved

The issue was that json arrays were not properly unmarshalled during
scanning the rows into structs.

## Additional changes

The issue could also happen on login names, therefore it got fixed for
this field too. Other fields are not affected because we use
`json.RawMessage` for the specific user types.

## Additional information

Introduced in https://github.com/zitadel/zitadel/pull/10967

backend/v3/storage/database/repository/instance.go

@@ -270,7 +270,7 @@ func (i instance) UpdatedAtColumn() database.Column {
 
 type rawInstance struct {
 	*domain.Instance
-	Domains JSONArray[domain.InstanceDomain] `json:"domains,omitempty" db:"domains"`
+	Domains JSONArray[*domain.InstanceDomain] `json:"domains,omitempty" db:"domains"`
 }
 
 func scanInstance(ctx context.Context, querier database.Querier, builder *database.StatementBuilder) (*domain.Instance, error) {