[ntuple, DAOS] maximum cage size should be part of the anchor

### Check duplicate issues.

- [x] Checked for duplicates

### Description

The DAOS backend should store the maximum cage size in the anchor. That will make reading individual sealed pages easier.

### Reproducer

n/a

### ROOT version

master

### Installation method

From sources

### Operating system

n/a

### Additional context

_No response_