Make ci_run_n_monitor useful by default

Currently ci_run_n_monitor requires you to pass --force-manual to enable manual jobs, such as full/ASan jobs only run on nightly, or known-flaky jobs, or whatever. This is good, because it means you won't accidentally DoS all the machines by spamming full jobs at them.

Unfortunately, all jobs in MR branches - the exact place you'd want to use ci_run_n_monitor - are also manual. So everyone has to use force-manual and rely on the regex getting it right, which they often don't.

To make things more useful to people, we move post-merge jobs into post-merge stages, and add stage filtering (both inclusive and exclusive) to ci_run_n_monitor. By default, rnm will ignore post-merge and performance jobs, so if you want to know if all the Panfrost jobs launched by Marge would pass, you just run ./ci_run_n_monitor.py --target 'panfrost.*'. Or if you want to know if all the Freedreno jobs launched by Marge would pass, you run ./ci_run_n_monitor.py --target '.*' --include-stage freedreno.