fix default ironic image build parameters

Change-Id: Ic0cb46e9f3356f8e782c88b5b75efe5bacee8bf5
diff --git a/jjb/metal3/projects.yml b/jjb/metal3/projects.yml
index abc599c..c4bc5af 100644
--- a/jjb/metal3/projects.yml
+++ b/jjb/metal3/projects.yml
@@ -276,8 +276,8 @@
     proj:
       - project_infra:
           repo: project-infra
-          branch: '${{ghprbActualCommit ?: main}}'
-          ci_github_repo: '${{ghprbAuthorRepoGitUrl ?: https://github.com/metal3-io/project-infra.git}}'
+          branch: '${{ghprbActualCommit}}'
+          ci_github_repo: '${{ghprbAuthorRepoGitUrl}}'
       - ironic_image:
           repo: ironic-image
     jobs: