This is a cosmetic fix. WT-13563 updates protoypes.py to create module-specific header files in the modules folder (e.g. src/evict/evict.h)

As part of this src/include/wt_internal.h needs to include the header files, but it does so with "#include ../evict/evict/h" which is a bit ugly. It'd be nicer to remove the relative path and use "#include "evict/evict.h".

To fix this we need to update CMake to add wiredtiger/src to the include path. I have a branch for this (linked in the comments) but there are TODOs that require further investigation. We also need to update mongo/src/third_party/wiredtiger/BUILD.bazel before we can merge this change into WiredTiger.