fix: Epi pre-job check is more robust.

The pre-job is meant to exit quietly if the prerequisite data is not
available yet. However, the epi pre-job check was raising an error
if AlternativeSuccessFileTemplate was missing from the config for
either Deposition or Environment. This is now handled quietly too.
CAUTION: This means the epi component will never raise an error
for missing input data, i.e., no email will ever say epi has failed to
run.