registry-auth is parsed as YAML, so `ecr: false` (unquoted) is the
boolean false, and `auth.ecr || 'auto'` turned it into 'auto'. For an
ECR registry this runs the AWS SDK login with the given username and
password as AWS access keys, instead of the plain docker login the user
asked for. Only the quoted string "false" worked.
Convert the value to a string and only default to 'auto' when it is
missing or empty.
Assisted-By: Claude
Signed-off-by: breken-ai <312387581+breken-ai@users.noreply.github.com>
