- Updates the image to use Ubuntu Jammy. - Installs GCC-12 as preparation to migrate to that GCC version. NOTE: This is a re-application off2f0dba818, which was reverted in2b5e3ef83cdue to an issue with the CI nodes. The CI nodes have since then been updated and this appears to be fine. Differential Revision: https://reviews.llvm.org/D126666