Use '${user}' as placeholder for the username

Placeholders in the format '${placeholder}' are commonly used in
Gerrit and we should use the same format here, especially since we
already have a second placeholder '${size}'.

Since we just created the project newly to fix the project name, it's
a good opportunity to change the placeholder as well.

Change-Id: Ie41915171bfb88ddc2a3818fec43d769c82137a0
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>