Currently our dist/s_docs script only supports doxygen 1.8.17 and 1.9.3. We used to support all versions of doxygen 1.9.X but changed this (WT-10195) due to doxygen 1.9.5 reporting false positives.

Our new ARM workstations come with doxygen 1.9.1 pre-installed and I haven't a clean way to get an ARM64 compatible binary of 1.8.17 for the platforms.

Instead - knowing that we previously supported all 1.9.X versions and only 1.9.5 is a problem - we can re-enabled 1.9.1 in s_docs.

Scope of work: Allow doxygen 1.9.1 in s_docs and update the Doxyfile.9 config to work with doxygen 1.9.1