Exclude GAM paths from Prebid refresh auctions

[ChristianPavilonis]

Description

Trusted Server currently creates a Prebid refresh auction for every GPT slot. Some tracking-only GAM slots must still refresh in GAM but should not enter that auction.

Expected behavior

• Operators can configure exact GAM ad-unit-path suffixes to exclude from Trusted Server refresh auctions.
• Matching slots retain their GPT refresh and stale Trusted Server/Prebid targeting is cleared.
• Normal slots continue to auction, including mixed global refreshes.
• Missing or failing GAM path metadata fails open.

Acceptance criteria

• Configuration validates suffixes and injects them into the managed Prebid browser config.
• Explicit, global all-excluded, and mixed refreshes have the intended GAM and Prebid behavior.
• Initial-load refresh pass-through remains unchanged.
• Operator documentation covers matching and external bundle rollout.