Exclude suspended providers from docs-list-as-string

[yuseok89]

related: #61926

When provider files change, selective checks builds docs-list-as-string from affected providers and their dependencies. Suspended providers (e.g. apache.beam) were included in this list.

In #62791 , docs build CI failed because apache.beam was included via Google provider dependencies.
This PR filters suspended providers from docs_list_as_string using get_suspended_provider_ids() before passing to the docs build.

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[potiuk]

Nice!