Adding 2 extra requirements to the backup submission

[kylesoskin]

Summary

• This adds 2 additional checks before sending a 526 backup submission
  -- It is a overall 526 submission, not an upload job
  -- it does not already have a claim ID (through RRD process?)
• This avoid duplicate 526 backup submissions
• Decision Review Team owns it currently, Benefits Experience team will own at some point
• uses a flipper, that is already flipped on: form526_backup_submission_temp_killswitch

Related issue(s)

department-of-veterans-affairs/va.gov-team#50111

Testing done

• local testing, existing rspec tests to test backup submission still gets sent

What areas of the site does it impact?

backend, sidekiq

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• Events are being sent to the appropriate logging solution
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Feature/bug has a monitor built into Datadog or Grafana (if applicable)
• If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• I added a screenshot of the developed feature