Update sample-rc to reflect changes to defaults

Defaults to settings and comments have changed but are not being reflected in the sample-rc which populates a user's kdesrc-buildrc file when running --initial-setup.

This is especially important as potential new contributors are instructed to run ./kdesrc-build --initial-setup, and this leaves them in a less than ideal state; for example the compile_commands.json will not be populated by default, therefore there will be no LSP support as expected with !100 (merged) .

This change brings the inital config more in line with the defaults generated when running kdesrc-build-setup.