Report output ccache errors getting initial creds

In init_creds_step_reply, if we get an error storing output
credentials, do set ctx->complete (since retrieving creds or times
will work at this point) but don't suppress the error code.

ticket: 8028 (new)
target_version: 1.13.1
tags: pullup
Add test for kinit output ccache error

ticket: 8028