[Bug]: ListTaskPushNotificationConfig paging is not coherent with ListTasks paging

### What happened?

In ListTasksRequest, the page size is defined as:
```
// Maximum number of tasks to return. Must be between 1 and 100.
// Defaults to 50 if not specified.
optional int32 page_size = 3;
```
while in ListTaskPushNotificationConfigRequest:

```
// The maximum number of configurations to return.
int32 page_size = 2;
```

I think both should be handled in the same way

### Relevant log output

```shell

```

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