Port PR from PBS-Go: Update dockerfile to use Ubuntu 22.04 as base image

[cross-repo-issue-creation]

A PR was merged over on PBS-Go

• Update dockerfile to use Ubuntu 22.04 as base image prebid-server#4252
• timestamp: 2025-03-24T20:47:35Z

[Net-burst]

PBS/PBC-Java recently did something similar, so closing.

• Docker: Update base Docker image version #3847
• Docker: Update base Docker image prebid-cache-java#160