Description of problem:

ceph-ansible sets expected_num_objects unexpectedly when creating pools


Version-Release number of selected component (if applicable):


How reproducible:
100%

Steps to Reproduce:
- Deploy a ceph cluster and ask ceph-ansible to create openstack pool(s) (or cephfs pool)


Actual results:
The command executed is as the following one:

ceph --cluster ceph osd pool create volumes 32 32 replicated_rule 1

which is incorrect.

Expected results:

ceph-ansible to create osd pool using the right syntax as documented [1]

[1] https://docs.ceph.com/docs/nautilus/rados/operations/pools/#create-a-pool

From the documentation, the osd pool creation command is :

```
ceph osd pool create {pool-name} {pg-num} [{pgp-num}] [replicated] \
     [crush-rule-name] [expected-num-objects]
ceph osd pool create {pool-name} {pg-num}  {pgp-num}   erasure \
     [erasure-code-profile] [crush-rule-name] [expected_num_objects]
```

it means we pass '1' (from item.type) as value for
`expected_num_objects` by default which is very likely not what we want.