[FLINK-36332] fix if syntax

Author: SamBarker

.github/workflows/e2e.yaml

@@ -59,7 +59,7 @@ jobs:
           docker build --progress=plain --no-cache -f ./Dockerfile -t flink-kubernetes-operator:ci-latest --progress plain --build-arg JAVA_VERSION="${JAVA_VERSION:-11}" --build-arg HTTP_CLIENT="${HTTP_CLIENT:-okhttp}" .
           docker images
       - name: Create ${{ inputs.namespace }} == ${{ inputs.create-namespace }}
-        if: inputs.create_namespace
+        if: ${{ inputs.create_namespace }}
         run: |
           source e2e-tests/utils.sh
           create_namespace flink