Stats: Remove state list request persistence.

[timmyc]

This branch fixes an issue introduced in #11035 that causes a stats page to become "stuck" on an old set of data. The auto-refresh feature introduced in the branch currently persists the state of the state.stats.lists.requests subtree, which allows the status of various stats API requests to be permanently stuck in a pending state.

When a given query for a stats endpoint is set to pending in the state tree, the <QuerySiteStats /> component will not issue any further API requests that match the endpoint/query that is set to pending. As such the only way for a user to fix this problem currently is to delete indexedDB manually, or log out.

It is helpful to reproduce the issue for yourself to properly test out this branch:

To Reproduce The Issue

• Open a site stats page for today ( DAY )
• Wait for the next refresh to trigger in 3 minutes, by closely watching the network tab in your dev console. It helps to have a filter set to XHR and “top-posts”

• Immediately close the browser tab while the requests are in-flight. This will persist the pending state in redux.
• Reopen the same site stats page. Note that the last updated timestamp is stuck, and if you wait 3 minutes, it will not update

There are other ways to get to this state, but I found the above to be the easiest way to reproduce the problem.

To Test the Fix
Run this branch locally, and follow the same steps. Upon reloading the stats page in the last step, the last updated timestamp should be current, and it should update as expected in 3 minutes

[matticbot]

Test live: https://calypso.live/?branch=fix/stats/stuck

[aduth]

Will want to remove the exported requestsSchema from ./schema since it's no longer used.

[youknowriad]

Good catch timmy, Tks. The reason I persisted the resquests is to keep the last update date visible on the page. Since the data is shown (from persisted state), I figured we should also show the date of this data.

What if we keep persistence or tweak the serialize action to drop pending requests? One other option is to separate the date into its own reducer.

[timmyc]

The reason I persisted the resquests is to keep the last update date visible on the page. Since the data is shown (from persisted state), I figured we should also show the date of this data.

I can see the reasoning here, but seems like the latest date will still be shown after the first request to top-posts is complete. In my testing it still felt okay without persistence. This bug is affecting multiple users in production now so I'd rather just remove the persistence and revisit during a future stats iteration.

Removed the schema in 51922c4 @aduth

[youknowriad]

LGTM 🚢