fixed rule object to yaml conversion for timeframe (#1020)

Signed-off-by: Amardeepsingh Siglani <amardeep7194@gmail.com>
(cherry picked from commit 2b1c6f1)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

public/pages/Rules/components/RuleEditor/DetectionVisualEditor.tsx

@@ -253,7 +253,9 @@ export class DetectionVisualEditor extends React.Component<
       let selectionMaps: any = {};
 
       selection.data.forEach((datum) => {
-        if (datum.field) {
+        if (selection.name === 'timeframe') {
+          selectionMaps = datum.values[0] || '';
+        } else if (datum.field) {
           const key = `${datum.field}${datum.modifier ? `|${datum.modifier}` : ''}`;
           selectionMaps[key] = datum.values;
         } else {