Move DoS related images from UBI8 to UBI9

[shaun-nx]

Release 4.4 of AppProtect DoS adds support for RHEL 9.

This issue is to move our DoS related builds from RHEL 8 to RHEL 9.

UACs

Beta Give feedback

1. Update Dockerfile to build DoS releated images from UBI 9
2. Remove references to app-protect-dos-8.repo file in cs.nginx.com repo
3. Add new app-protect-dos-9.repo repo file for pulling RHEL 9 supported AppProtect DoS files

[github-actions]

Hi @shaun-nx thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!