As stated in #27151, it would be great to reduce the number of examples in the gallery.

Right now, we have three examples for:

• OPTICS: https://scikit-learn.org/dev/auto_examples/cluster/plot_optics.html#sphx-glr-auto-examples-cluster-plot-optics-py
• DBSCAN: https://scikit-learn.org/dev/auto_examples/cluster/plot_dbscan.html#sphx-glr-auto-examples-cluster-plot-dbscan-py
• HDBSCAN: https://scikit-learn.org/dev/auto_examples/cluster/plot_hdbscan.html#sphx-glr-auto-examples-cluster-plot-hdbscan-py

Those clustering methods are really close to each others; some being an improvement from another one. Therefore, we could rework a single example that is not only a demo but rather show the pros & cons from each approach.