This commit removes the raw:: html directive (with the exception of an embedded animation) because:
- It is not supported by the dark theme and looks bad.
- It's a legacy directive, and we no longer need it on index pages.
Fixes https://github.com/scylladb/scylladb/issues/20881Closesscylladb/scylladb#21062
b54ce3b0c0
