Relax redundant Pages object storage validation from specs and templates

What does this MR do?

Relax redundant Pages object storage validation from specs and templates

!5124 (merged) fixed and tightened the consolidated object store config check for GitLab Pages. As a side effect, it broke previously valid configurations: when both consolidated object storage and the Pages-specific objectStore are set, the check now fails — even though the Pages-specific config is simply superseded by the consolidated config and caused no harm before.

This relaxes the check to avoid that breaking change.

Related issues

Related: #6531 (closed)

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