ActivityCards Template: Fix build

The ActivityCards template was outputting resource names containing
spaces. This fixes that error by removing whitespace from the
template.

Change-Id: Iacccc0d53975e4c08b3b54498fbe1415a5a1e2b6
diff --git a/templates/ActivityCards/ActivityCardsCommon.ftli b/templates/ActivityCards/ActivityCardsCommon.ftli
index 93ea4dd..08745cd 100644
--- a/templates/ActivityCards/ActivityCardsCommon.ftli
+++ b/templates/ActivityCards/ActivityCardsCommon.ftli
@@ -14,6 +14,4 @@
         See the License for the specific language governing permissions and
         limitations under the License.
 -->
-<#macro make_activity_res activity type>
-    ${(activity.class!"activity_class")?lower_case}_${type}
-</#macro>
+<#macro make_activity_res activity type>${(activity.class!"activity_class")?lower_case}_${type}</#macro>