Normalize PBJS and PBS auction IDs

[bretg]

Type of issue

enhancement

Description

Trying to coordinate analytics between PBJS and PBS is made more difficult by their not having a common ID for the auction event.

• PBJS supports an 'auctionId' which is unique for each Auction refresh
• But the Prebid Server Bid Adapter sets $.id to s2sBidRequest.tid.

I propose that we change the PBS bid adapter to use the PBJS auctionId as REQUEST.id for all PBS servers instead of having different REQUEST.id values for each of an array of prebid servers.

We should also set source.tid be the same across all Prebid Servers.