[Lens] fix flaky test with deleting filters (elastic#191316)

## Summary

Fixes elastic#191009

(also fixes elastic#189569
elastic#178270
elastic#139040 which are already closed
as one time occurances but could happen again)

https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/6809

test/functional/services/filter_bar.ts

@@ -133,10 +133,11 @@ export class FilterBarService extends FtrService {
    * @param key field name
    */
   public async removeFilter(key: string): Promise<void> {
-    await this.retry.try(async () => {
+    await this.retry.waitFor('filter pill context menu is open', async () => {
       await this.testSubjects.click(`~filter & ~filter-key-${key}`);
-      await this.testSubjects.click(`deleteFilter`);
+      return await this.testSubjects.exists('deleteFilter');
     });
+    await this.testSubjects.click(`deleteFilter`);
     await this.header.awaitGlobalLoadingIndicatorHidden();
   }