Add -detach_after_tracing feature to drcachesim

For a limited-duration trace, we first implemented -max_trace_size, but it's kind of useless outside of tests as it's per-thread. We later added -exit_after_tracing, but it doesn't work well with some setups where we have logic inside the app (typically using static-linked drcachesim) that needs to take some steps after DR exits. We also have -max_global_trace_refs but it has a time gap problem: #5021. For our use case what we want is a detach when a max size is reached. This requires #2644.

Start by reading drcachesim's handling of -max_trace_size, -exit_after_tracing, and -max_global_trace_refs, along with the requirements in #2644. The feature is done when drcachesim detaches after reaching the requested maximum trace size, while allowing application logic to continue after DynamoRIO exits.

Written by the indexing model from the issue text.