vzdump: storage info: move out activate storage call

vzdump: storage info: move out activate storage call

Otherwise storage_info() cannot be used for (at least) PBS storages from an API
call without 'protected => 1', because the password cannot be read from
'/etc/pve/priv'. Note that the function itself does not need the storage to be
active, because it only uses storage_config() and get_backup_dir().

AFAICT new() is the only existing user of this function and can be responsible
for activating the storage itself.

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>