fix: respect search_methods configuration in edge_search and node_search
The search functions were ignoring the configured search_methods and
always executing all three methods (BM25, cosine similarity, and BFS).
This was causing unnecessary performance overhead - running 3x the
required computations when users only wanted specific search methods.
Now the functions build search tasks dynamically based on what's
actually configured in search_methods, only executing the requested
search algorithms.
This should significantly improve performance when users need only
specific search methods. Would appreciate your review on this approach\!
Fixes#788
506bc4fc98