CI: Drop some jobs we didn't really utilize

- We have added more TODO/etc comments since this task was created and
  never focused on removing them.
- The output of sloccount isn't preserved or looked at, and if desired
  should be in the release stats pages instead somehow.
- The results of cppcheck aren't investigated and require modeling work
  to be useful to start with.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>