claim_search: Don't clear past page results if subsequent pages timeout.

## Issue
4609: If claim search on latter page fails, don't clear out all previous data

## Note
This requires an accompanying change in `lbry-redux` to mark `claimSearchResultLastPageReached` during timeout and to not purge past results.

## Change
The previous flow was: increment the page, and expect the next render to either be 0 (timeout + purge) or fill in at least 1 new item.

Since it is now possible for no results to be returned for the new page (due to timeout + no purging), the code continues to make another query. This commit stops the perpetual querying.

## Test Case:
1. https://lbry.tv/$/discover?t=imherelbry&content=video&order=top&fresh=year
2. Scroll down a few pages until it timeout happens. Past results are gone.

CHANGELOG.md

@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
 
 - Loss of subscriptions on startup ([#4882](https://github.com/lbryio/lbry-desktop/pull/4882))
+- Fix lost search results when a timeout occurs _community pr!_ ([#4996](https://github.com/lbryio/lbry-desktop/pull/4996))
 
 ## [0.48.2] - [2020-10-16]
 

ui/component/claimListDiscover/view.jsx

@@ -356,6 +356,7 @@ function ClaimListDiscover(props: Props) {
     claimSearchResult === undefined ||
     didNavigateForward ||
     (!loading &&
+      !claimSearchResultLastPageReached &&
       claimSearchResult &&
       claimSearchResult.length &&
       claimSearchResult.length < dynamicPageSize * options.page &&