Disable rugged auto-detect when Puma threads>1

What does this MR do?

#119326 (closed)

During Puma opt-in phase, we want to disable rugged auto-detect when puma threads>1, for two reasons:

• we know Rugged patches + Puma multi-thread will degrade performance. Because Rugged does not release GVL while doing IO work.
• we expect Puma(theads>1) + Gitaly would give reasonable performance.

The auto-detect disable logic happen in use_rugged?, after Feature flag check and before Gitlab::GitalyClient.can_use_disk?. The logic is skipped when Feature flag is explicitly set. So user still have choice to explicitly enable/disable use_rugged? by Feature flag(:rugged_commit_is_ancestor, :rugged_tree_entry, :rugged_find_commit, :rugged_list_commits_by_oid, :rugged_commit_tree_entry,:rugged_tree_entries).

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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