fix: missing server affinity

[jfcoz]

Description

Also use affinity in trivy-server statefulset

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[github-actions]

This PR is stale because it has been labeled with inactivity.