Adopt with grafana_network not grafana_server_addr (backport #7654)

[mergify]

The networks list in a spec is usually a range not a single IP. grafana_server_addr is a fact created from grafana_network so it is a more appropriate parameter to pass.

Follow up to 770a527

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This is an automatic backport of pull request #7654 done by Mergify.

[mergify]

Cherry-pick of b1f7e2d has failed:

On branch mergify/bp/stable-9.0/pr-7654
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	both modified:   infrastructure-playbooks/cephadm-adopt.yml

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