Fix typo in username tag

[albertvaka]

What does this PR do?

Fixes that instead of using the USER_NAME constant (which evaluates to user.name), we were using the string literal username.

Review checklist (to be filled by reviewers)

• Feature or bug fix MUST have appropriate tests (unit, integration, etc...)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
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