Aliases should not usersync with their own cookie family if they share the base sync URL

[bretg]

PBS-Go version of https://github.com/prebid/prebid-server-java/issues/2702

@patmmccann found that the YAML files in PBS-Java are set up so that bidder aliases are syncing on their own, which is inefficient and takes up extra space in the uids cookie.

This will be fixed in a forthcoming version of PBS-Java, but opening this issue for community discussion and probably a bidder docs update.

Discussed in committee:

• do we need to worry about the edge case where an alias has a different ID from the base adapter?
• since there will still most likely be an ID for the aliases, it's not clear this is a breaking change
• the committee is proposing to not build in transition period logic. We would warn host companies to monitor the potential match rate impact to aliased adapters.

[bretg]

We will consider this for 1Q23. Don't want to affect Q4 revenue for anyone.