Fix error message to use subject_name

[minionOfZuul]

The "schema name" returned by default_schema_record_name isn't helpful in identifying which subject can't be found. This PR updates the error message to use the subject name.

[acima-infosec-github-appsec]

Hi, I noticed this repo does not have all of the required topics applied to it. In order to organize repos at Acima, all repos need to have several topics that describe the nature of the repo. Please apply the topics as specified by the confluence article here: https://acima.atlassian.net/wiki/spaces/SEC/pages/313622545/Why+did+I+get+comments+on+my+PR

You are missing the following topics:

• The data topic in the format of 'data-<data_type>
  Possible values are:
  data-non-prod
  data-prod-customer
  data-prod-systems
• The type topic in the format of 'type-<data_type>
  Possible values are:
  type-service
  type-library
  type-sample
  type-other