[Logs Explorer] Functional tests: Complete cleanup before continuing …

…with the next tests (elastic#175517)

This [functional
test](https://github.com/elastic/kibana/blob/b25407edba0bb146c37d74b24e01d8c6367bfa64/x-pack/test/functional/apps/observability_log_explorer/dataset_selector.ts#L311)
was failing locally, as it was expecting the integration to be `Apache
HTTP Server` but was in fact `1password`. This is because the previous
test loads more integrations (than the original 3) and sometimes it
doesn’t clean up in time before the next test runs.

This PR adds `await` on the async
[cleanupAdditionalSetup](https://github.com/elastic/kibana/blob/main/x-pack/test/functional/apps/observability_log_explorer/dataset_selector.ts#L298)
call to complete the cleanup before continuing with other tests.

x-pack/test/functional/apps/observability_log_explorer/dataset_selector.ts

@@ -295,7 +295,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
             expect(nodes.length).to.be(20);
           });
 
-          cleanupAdditionalSetup();
+          await cleanupAdditionalSetup();
         });
 
         describe('clicking on integration and moving into the second navigation level', () => {

x-pack/test_serverless/functional/test_suites/observability/observability_log_explorer/dataset_selector.ts

@@ -296,7 +296,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
             expect(nodes.length).to.be(20);
           });
 
-          cleanupAdditionalSetup();
+          await cleanupAdditionalSetup();
         });
 
         describe('clicking on integration and moving into the second navigation level', () => {