Fix problem with pr pipeline. Used wrong variable in template. (#5683)

diff --git a/ci/pipelines/pull-request/jinja.template.yml b/ci/pipelines/pull-request/jinja.template.yml
index 7a5edef..8e4d208 100644
--- a/ci/pipelines/pull-request/jinja.template.yml
+++ b/ci/pipelines/pull-request/jinja.template.yml
@@ -155,7 +155,7 @@
             - name: geode-ci
             - name: attempts-log
               path: old
-            - name: {{ test.PLATFORM}}-builder-image-family
+            - name: {{ build_test.PLATFORM}}-builder-image-family
               path: builder-image
             outputs:
             - name: instance-data