Port PR from PBS-Go: Adkernel: rxnetwork alias

[cross-repo-issue-creation]

A PR was merged over on PBS-Go

• Adkernel: rxnetwork alias prebid-server#3956
• timestamp: 2024-12-10T01:14:28Z

[bretg]

@katherynhrabik - Note that in PBS-Java we don't generally create new files for aliases. Rather, we would just add rxnetwork as an alias in the existing adkernel.yaml file. I think this would be like yahooAds.yaml