[BE] 10-10EZR - Standalone form: Investigate issue found in DD trace logs on all submissions

[hdjustice]

Background

For all the EZR submissions, there is an error/warning event after the successful submission that states Unrecognized value for HTTP_SOURCE_APP_NAME request header

We need to investigate this issue and determine the root cause, how we might avoid it from firing and confirm there has been no negative impact to the Veterans.

Tasks

• [x] Investigate Datadog issue
• [x] Determine root cause - notate in comments if the root cause is found, & what is it, OR if it is not found.
• [x] Determine solution, if root cause is found
• [x] Determine impacts to Veterans (if any)

Acceptance Criteria

• Datadog issue found during EZR submissions is investigated

[jadon1979]

ezr was not added as a frontend app to the statsd middleware. This entry is needed to whitelabel ezr for sentry. There is no impact to the veteran for this issue.

https://github.com/department-of-veterans-affairs/vets-api/pull/14955