SpringBoot Upgrade CI image update detection to Ubuntu Jammy

Hi,

this PR updates the detect-ubuntu-image-updates.sh script to check for updates on Jammy rather than Focal. The former is the LTS version since April 2022.

I didn't update the CI images on purpose since the script should pick this up, but let me know if I should directly do this.

Cheers, Christoph

Comment From: wilkinsona

Thanks, @dreis2211.