GH-118093: Better handling of short and mid-loop traces

[brandtbucher]

This makes two changes to trace projection:

• Handle a single backward jump anywhere in a trace, rather than just at the beginning.
• Rather than having a minimum trace length, just ensure that at least one instruction is fully translated. This prevents us from requiring the translation of several tiny instructions or "successfully" half-translating a large instruction.

Perf is neutral, but stats move in the right direction: 83% reduction in "inner loop found", 7% reduction in "trace too short", and 5% fewer optimization attempts overall. We execute 0.5% more uops and 0.5% fewer traces. 2% fewer tier one instructions executed overall.

• Issue: Increase fraction of code executed by tier 2. #118093

[markshannon]

A couple of questions

[markshannon]

Can you:

• Go back to removing the asserts, and leave is_resume alone.
• Add a comment linking to #122390

Consider it approved once you've done that

[bedevere-app]

When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.