[services][blob] Let database helpers use new errors

Summary:
Use previously defined errors in database code.

Depends on D5856

Test Plan: Purposefully caused a few attribute errors (e.g. saved blob with invalid timestamp format) to ensure they are handled correctly.

Reviewers: varun, jon, tomek, michal

Reviewed By: varun, jon, tomek

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D5857