[train][harbor] Suppress excessive harbor/litellm loggings

[CharlieFRuan]

This PR removes excessive loggings:

• From Harbor, via two new flags suppress_max_turns_warning and suppress_override_warnings
• Suppresses the per-trial warnings about environment overrides and turn overrides (4 lines per rollout)
• From LiteLLM (via Harbor), with litellm.suppress_debug_info, set_verbose, and logger level to warning for LiteLLM
  • Suppresses model provider log, trivial per-request log, etc.

In addition, rename max_episodes to max_turns.

Depends on laude-institute/harbor#561

[gemini-code-assist]

Code Review

This pull request aims to reduce excessive logging from Harbor and LiteLLM. It introduces new configuration flags in default.yaml to suppress Harbor warnings and renames max_episodes to max_turns. For LiteLLM, it adds code to terminal_bench_generator.py to suppress debug info and set the log level. The changes in the YAML configuration are straightforward and look correct. However, the Python change introduces module-level logging configuration, which can cause unintended side effects. I've added a comment with a suggestion to improve this by moving the configuration logic. My review also points out a deviation from the PEP 8 style guide regarding the placement of imports.