Add back in docker targets.

.webhook_bridge/pipeline-build-homepage-staging.yaml

@@ -136,6 +136,8 @@ spec:
             value: $(params.path-to-dockerfile)
           - name: EXTRA_ARGS
             value:
+              - "--opt"
+              - "target=$(params.target-name)"
               - --import-cache
               - "type=registry,ref=$(params.image-name):buildcache"
               - --export-cache

.webhook_bridge/pipeline-build-homepage.yaml

@@ -148,6 +148,8 @@ spec:
             value: $(params.path-to-dockerfile)
           - name: EXTRA_ARGS
             value:
+              - "--opt"
+              - "target=$(params.target-name)"
               - --import-cache
               - "type=registry,ref=$(params.image-name):buildcache"
               - --export-cache