The configuration subconfiguration name "prefetch" has caused a problem when enabling WT_SESSION->reconfigure for compiled configuration, presumably because prefetch is also used in WT_CONNECTION->reconfigure.  There's a workaround around this used in WT-13454 that matches specifically on the name "prefetch".  We should be able to do better - we might have to indicate in api_data.py that for a given name, there is an explicit C name that should be used for names of structs/defines etc.