Fix prerequisites in cephadm-preflight (backport #308)

[mergify]

I noticed that clients configured with cephadm-preflight.yml were not getting prerequisite packages installed. This was due to a wrong conditional in the playbook.

Also lvm2 is an official prerequisite as per the docs so I added it to the infra packages in the defaults as not all distros in all feature-flavors come with it installed.

There is still the problem, that the clients group is left untouched by the preflight playbook. This is also fixed my this PR.
Here a comparison in playbook runs. Here rocky9-01 is admin, but not client and osd. The rest (02-04) is admin, client and osd.

existing prefligt playbook

TASK [install prerequisites packages on servers]
ok: [rocky9-01.testcluster.local]                     
changed: [rocky9-03.testcluster.local]                
changed: [rocky9-02.testcluster.local]                
changed: [rocky9-04.testcluster.local]                
                                                
TASK [install prerequisites packages on clients]
skipping: [rocky9-01.testcluster.local]               
skipping: [rocky9-02.testcluster.local]               
skipping: [rocky9-03.testcluster.local]               
skipping: [rocky9-04.testcluster.local]                  

As you can see, the clients are skipped, no packages are installed.

proposed preflight playbook

TASK [install prerequisites packages on servers]
changed: [rocky9-04.testcluster.local]                
changed: [rocky9-03.testcluster.local]                
changed: [rocky9-01.testcluster.local]                
changed: [rocky9-02.testcluster.local]                
                                                
TASK [install prerequisites packages on clients]
skipping: [rocky9-01.testcluster.local]               
ok: [rocky9-04.testcluster.local]                     
ok: [rocky9-02.testcluster.local]                     
ok: [rocky9-03.testcluster.local]                     

The clients are now not immediately skipped anymore and the required packages are installed.

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This is an automatic backport of pull request #308 done by Mergify.