chore: rm unused code

[maelle]

No description provided.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if db34151 is merged into main:

• ✔️as_adjacency_matrix: 758ms -> 757ms [-0.77%, +0.36%]
• ✔️as_biadjacency_matrix: 734ms -> 735ms [-0.48%, +0.58%]
• ✔️as_data_frame_both: 1.46ms -> 1.48ms [-0.48%, +2.58%]
• ✔️as_long_data_frame: 3.88ms -> 3.97ms [-3.04%, +7.68%]
• ✔️es_attr_filter: 2.65ms -> 2.68ms [-0.25%, +2.33%]
• ✔️graph_from_adjacency_matrix: 118ms -> 119ms [-0.95%, +1.9%]
• ✔️graph_from_data_frame: 3.37ms -> 3.3ms [-5.01%, +1.28%]
• ✔️vs_attr_filter: 1.51ms -> 1.51ms [-2.02%, +2.55%]
• ✔️vs_by_name: 968µs -> 967µs [-1.67%, +1.36%]
  Further explanation regarding interpretation and methodology can be found in the documentation.