Update GitLab Runner Ubuntu support matrix to pin to end of standard support
What does this MR do?
Update GitLab Runner Ubuntu support matrix to pin to end of standard support.
Why was this MR needed?
In this Slack thread, we were made aware that we had pinned the end of support date for Ubuntu 20.04 to Ubuntu's end of legacy support date, which for that version of Ubuntu is April 2032. We cannot maintain older versions of the runner helper image for that extended period of time. Therefore this MR proposes changing the end of support date to align with Ubuntu's end of standard support date.
Edited by Darren Eastman