feat(planning): enhance planning configuration and observation handling (#5913)

* feat(planning): enhance planning configuration and observation handling

- Introduced  attribute in  to control LLM calls after each step.
- Updated  to set default  to 1 when planning is enabled without explicit config.
- Modified  to support heuristic observations when LLM calls are disabled.
- Adjusted  to respect  and  settings for step observations.
- Added tests to verify behavior of new configurations and ensure correct observation handling across different reasoning efforts.

* fix(agent_executor): update handling of failed steps in low effort mode

- Adjusted logic to ensure that failed steps are recorded without marking them as completed when using low reasoning effort.

- Introduced feedback for failed steps, allowing the process to continue while tracking failures.
- Added a test to verify that failed steps are correctly marked without triggering a replan.

- And linted

* linted