Migrate CI to Ubuntu 24

[goatgoose]

Problem:

Currently, the vast majority of the Codebuild CI jobs use a Ubuntu 18 image: https://github.com/aws/s2n-tls/blob/1ed5624c24c80b5ef93f93a72ee93b503ddd6eba/codebuild/spec/buildspec_generalbatch.yml#L22

This includes many of the unit test jobs that test combinations of compilers and libcryptos, and the integration test jobs.

In addition to adding a simple unit test job to Ubuntu 24 (https://github.com/aws/s2n-tls/issues/4529), all of the existing unit test combinations and the integration tests should be moved to Ubuntu 24. This will allow newer compiler versions to be more easily tested.

Solution:

Migrate the ubuntu 18 CI image to Ubuntu 24.

[dougch]

As with Arm/nix, tools like sslyze won't be simple to bring forward. Unit test runs should be trivial to get running with minor updates to the install_ubuntu_deps script.

[boquan-fang]

Pedantic Valgrind check will report still reachable errors for s2n_self_talk_ktls_test and s2n_fork_generation_number_test on Ubuntu 22 and 24. Hence, the new CTest memcheck still uses Ubuntu 18 for pendantic Valgrind check. See the end of this codebuild job for the exact issue.