[ML] Index data visualizer sometimes shows wrong doc count for saved searches

[pheyos]

Found in version

• 7.14.0-bc3

Browser

• Chrome

Steps to reproduce

1. Prepare a saved search that actually filters out some documents
   • e.g. use the ecommerce sample dataset, open it in Discover, search for customer_first_name : E* (which only returns 448 of the 4675 documents) and save the search
2. Navigate to the index data visualizer and select the saved search
3. Click the use full data button and verify that the reduced doc count is displayed
4. Go back to the Data Visualizer page, click select index pattern, select the same saved search again (it remembers the time range) and look at the doc count
5. Repeat step 4. a few times

Expected result

• After every load the reduced doc count is displayed

Actual result

• Sometimes the total doc count (without the search applied) is displayed:
  

Additional information

• In the network activity I can see two requests for the doc count on initial load: the first one without the search query and a second one with the search query. I guess the issue happens in cases where the first request runs slower than the second one and comes back later with the wrong result.
• Related to Failing test: Chrome X-Pack UI Functional Tests Basic License.x-pack/test/functional/apps/ml/data_visualizer/index_data_visualizer·ts - apps machine learning basic license data visualizer index based with farequote lucene saved search displays index details #105087 (related tests are currently skipped and should be re-activated with the fix PR)

[elasticmachine]

Pinging @elastic/ml-ui (:ml)