lsp: remove caching for config/source
lsp: remove caching for config/source

They are cheap in merlin so no need to cache them.

ocaml/merlin,the-lambda-church/merlin,rgrinberg/merlin,rgrinberg/merlin,ocaml/merlin,rgrinberg/merlin,dra27/merlin,the-lambda-church/merlin,rgrinberg/merlin,dra27/merlin,dra27/merlin,ocaml/merlin,ocaml/merlin,the-lambda-church/merlin,dra27/merlin