fix(agents-api): Add `mmr_strength` in search tools & increase timeout for `transition_step`

[HamadaSalhab]

[!IMPORTANT] Add mmr_strength to search requests and increase transition_step timeout based on environment in agents-api.

• Behavior:
  • Add mmr_strength parameter to _create_search_request() in execute_system.py for HybridDocSearchRequest, TextOnlyDocSearchRequest, and VectorDocSearchRequest.
  • Increase schedule_to_close_timeout for transition_step in transition.py to 600 seconds unless in debug or testing mode.
• Misc:
  • Import debug and testing from env in transition.py.

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[sweep-ai[bot]]

Hey @HamadaSalhab, here is an example of how you can ask me to improve this pull request:

@sweep Add unit tests for `_create_search_request` function to verify the new `mmr_strength` parameter is correctly handled for all three request types (HybridDocSearchRequest, TextOnlyDocSearchRequest, and VectorDocSearchRequest), including:
- Default value (0) when not provided
- Custom value when provided
- Proper removal of the parameter from arguments dictionary

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