Filtering metrics by labelSelector in external.metrics.k8s.io api doesn't work

Some metrics labels (like `resource.labels.instance_id` in my case) are longer than 63 characters and have forbidden characters like slashes which makes filtering by those labels impossible and thus whole `v1beta1.external.metrics.k8s.io` service unusable for big number of external metrics.

If I run this with simpler labels like `resource.labels.region` I will get external metrics for all redis instances in the region as expected:
```
kubectl get --raw "/apis/external.metrics.k8s.io/v1beta1/namespaces/*/redis.googleapis.com|stats|network_traffic?labelSelector=resource.labels.region=europe-west3" | jq .

{
"kind": "ExternalMetricValueList",
"apiVersion": "external.metrics.k8s.io/v1beta1",
"metadata": {},
"items": [
{
"metricName": "redis.googleapis.com|stats|network_traffic",
"metricLabels": {
"metric.labels.direction": "in",
"metric.labels.role": "primary",
"resource.labels.instance_id": "projects/test-project/locations/europe-west3/instances/production",
"resource.labels.node_id": "node-0",
"resource.labels.project_id": "test-project",
"resource.labels.region": "europe-west3",
"resource.type": "redis_instance"
},
"timestamp": "2023-04-19T09:28:42Z",
"value": "3945867400m"
},
...
{
"metricName": "redis.googleapis.com|stats|network_traffic",
"metricLabels": {
"metric.labels.direction": "in",
"metric.labels.role": "primary",
"resource.labels.instance_id": "projects/test-project/locations/europe-west3/instances/staging",
"resource.labels.node_id": "node-0",
"resource.labels.project_id": "test-project",
"resource.labels.region": "europe-west3",
"resource.type": "redis_instance"
},
"timestamp": "2023-04-19T09:28:42Z",
"value": "13748666m"
},
]
}
```

Problem is if I want to select metric for specific redis instance using `resource.labels.instance_id` label that is not in [allowed format](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set) then I get error:
```
kubectl get --raw "/apis/external.metrics.k8s.io/v1beta1/namespaces/*/redis.googleapis.com|stats|network_traffic?labelSelector=resource.labels.instance_id=projects/test-project/locations/europe-west3/instances/staging" | jq .

Error from server (BadRequest): unable to parse requirement: values[0][resource.labels.instance_id]: Invalid value: "projects/test-project/locations/europe-west3/instances/staging": must be no more than 63 characters; a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character (e.g. 'MyValue', or 'my_value', or '12345', regex used for validation is '(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?')
```

This makes horizontal pod autoscaling based on external metric impossible if you want to scale pods based on metrics from specific redis instance in the google cloud project.