Time window filter dropdown doesn't retain previously selected window

Summary

Time window filtering dropdown in Monitor dashboard doesn't retain the previously selected value. Selecting a value from the dropdown reloads the page as expected with the correct URL parameters. However, the dropdown doesn't pre-select the right time window in the dropdown.

Steps to reproduce

1. Open metrics dashboard for a project (assuming that Prometheus integration is enabled)
2. Select a different time window and it should reload the page. The time window filtering dropdown has 8 hours selected by default.
3. Notice that the page reloads with correct URL params but the time window dropdown shows wrong window as selected.

Relevant logs and/or screenshots

(Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's tough to read otherwise.)

Possible fixes

Anybody working on this should take a look at this line in utils.js https://gitlab.com/gitlab-org/gitlab/blob/master/app/assets/javascripts/monitoring/utils.js#L16