Some CI improvements

1. Remove build-large-originator job. It's intended to provide a portable executable for morley-large-originator, but the executable it builds still depends on dynamic libraries and would only work on the system it was built on. Instead we plan to build static executables in the future (#304 (closed)).
2. Avoid using ./. nix construct preBuild parameter for cleveland, because it results in the whole project directory (including .git) being copied to the nix store, and cleveland being rebuilt in each job, even in the same pipeline run, because .git contents may differ slightly. Use projectSrc instead, which filters out unrelated files.
3. Update conditions for real-chain tests so that they don't run in the scheduled pipelines for docker registry tests, and update local-chain tests so that they don't run in scheduled pipelines at all.
4. Use only/except instead of rules for job conditions. We switched to rules in b29b39c3, because gitlab was going to deprecate only, but now it looks like they decided to keep it and just mark it as not being actively developed (https://docs.gitlab.com/ee/ci/yaml/#only--except). And for our usecase only/except seem to be much simpler to understand and to maintain.
5. Add --color=always flag to tasty-based tests to make test results colored. I think it should make it easier to spot failed/succeeded tests in a job output (but if it's not a concern I can roll this change back).