[e2e] avoid use of unpinned ubuntu base image

This commit fixes the failing e2e tests observed in the main branch,
The root cause is the use of the unpinned "ubuntu" base image which has
moved to `resolute` (Ubuntu 26.04) which has new assumptions when it comes
to setting up a C build environment.

Signed-off-by: Tariq Ibrahim <tibrahim@nvidia.com>