storage: Using regional endpoints results in a `Transport: unhandled response frame type *http2.UnknownFrame` log from the http2 package

# Client

GCS

# Environment

```
go version go1.24.2 darwin/arm64

cloud.google.com/go/auth v0.16.4
cloud.google.com/go/storage v1.56.0
google.golang.org/api v0.246.0
```

# Code and Dependencies

```go
package main

import (
"bytes"
"context"
"io"
"log"

"cloud.google.com/go/auth/credentials/impersonate"
"cloud.google.com/go/storage"
"google.golang.org/api/option"
)

func main() {
ctx := context.TODO()

creds, err := impersonate.NewCredentials(&impersonate.CredentialsOptions{
TargetPrincipal: "",
Scopes: []string{"https://www.googleapis.com/auth/devstorage.read_write"},
})
if err != nil {
log.Fatalf("creating creds: %s", creds)
}

client, err := storage.NewClient(ctx,
option.WithAuthCredentials(creds),
option.WithEndpoint("storage.europe-west3.rep.googleapis.com"),
)

bucket := client.Bucket("")
bucket.Attrs(ctx) //

object := bucket.Object("file.txt")

testMessage := bytes.NewReader([]byte(`hello world!`))
w := object.NewWriter(ctx)
if _, err := io.Copy(w, testMessage); err != nil {
_ = w.Close()
log.Fatalf("writing to GCS bucket: %s", err)
}

if err := w.Close(); err != nil {
log.Fatalf("closing writing to GCS bucket: %s", err)
}
log.Print("uploaded successfully, closing storage client", client.Close())
}
```

# Behavior

Calls to `bucket.Attrs(ctx)` and `w.Close()` when supplying `option.WithEndpoint` result in http2 package logging `Transport: unhandled response frame type *http2.UnknownFrame`

The uploads are successful, but I don't know whether this log deserves any attention and if it doesn't then it is simply inflating my logs.