Duplicate "goal" descriptions in several prompt files

[doruit]

Description:

The following prompt files contain a duplicated "goal" description, likely due to a copy-paste or editing oversight. This can cause confusion when maintaining prompt content.

Affected files:

• basic_search_system_prompt.txt
• drift_reduce_prompt.txt
• drift_search_system_prompt.txt
• global_search_map_system_prompt.txt
• global_search_reduce_system_prompt.txt
• local_search_system_prompt.txt

Proposed fix: Remove the duplicated "goal" section from each affected file so that the goal is described only once.