Resolve "USAN:: OOB indexing in E_GAIN_closed_loop_search_fx function (EVS)"

• Related issues: sa4/audio/ivas-basop#2278 (closed)
• Requested reviewers:

Reason why this change is needed

• Fix out-of-bounds array indexing in closed loop pitch search

Description of the change

• change index handling to avoid seting OOB index.

Affected operating points

• None, all is BE
• slight complexity increase in the pitch search possible