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: Ib9dcbf21d0a28700d500cf0ea4e412b009758d5d
Signed-off-by: William Roberts <william.c.roberts@intel.com>