Populate BUILDAH_FORMAT where missing

See https://redhat-internal.slack.com/archives/C04PZ7H0VA8/p1760438547286539?thread_ts=1758912510.784729&cid=C04PZ7H0VA8
This is part of https://issues.redhat.com/browse/ROX-31049

Author: msugakov

.tekton/scanner-component-pipeline.yaml

@@ -340,6 +340,8 @@ spec:
       value: $(tasks.prefetch-dependencies.results.CACHI2_ARTIFACT)
     - name: PLATFORM
       value: linux/s390x
+    - name: BUILDAH_FORMAT
+      value: $(params.buildah-format)
     - name: LABELS
       value: ["$(params.extra-labels[*])"]
     - name: BUILD_TIMESTAMP
@@ -384,6 +386,8 @@ spec:
       value: $(tasks.prefetch-dependencies.results.CACHI2_ARTIFACT)
     - name: PLATFORM
       value: linux/ppc64le
+    - name: BUILDAH_FORMAT
+      value: $(params.buildah-format)
     - name: LABELS
       value: ["$(params.extra-labels[*])"]
     - name: BUILD_TIMESTAMP
@@ -428,6 +432,8 @@ spec:
       value: $(tasks.prefetch-dependencies.results.CACHI2_ARTIFACT)
     - name: PLATFORM
       value: linux/arm64
+    - name: BUILDAH_FORMAT
+      value: $(params.buildah-format)
     - name: LABELS
       value: ["$(params.extra-labels[*])"]
     - name: BUILD_TIMESTAMP