service_contexts: don't delete intermediate on failure

When service_contexts fails to build, the file is deleted
leaving only the error message for debugging. Build
service_contexts and general variant as a temporary
intermediate before running checkfc.

Change-Id: Ib9c9247d36e6a6406b4df84d10e982921c07d492
Signed-off-by: William Roberts <william.c.roberts@intel.com>