[Brave News]: Potentially refresh old data, if its stale when switching back to the news tab

[fallaciousreasoning]

Currently, if you open a tab and leave it open for a long time Brave News will show stale data. We should refresh the feed if the data is old.

cc @LorenzoMinto should we do 1 hour here (our stale data timeout) or 3 hours (our feed refresh rate)

1. Open a tab
2. Swap to another
3. Wait hours
4. Switch back

Expected
Feed is fresh

Actual
Feed is the same data as before

[LorenzoMinto]

Did we end up going with 1h or 3h?

[fallaciousreasoning]

1 hour to regenerate the feed - the backend will refetch data every 3 hours

So:
Fresh feed every hour
Fresh data every 3 (unchanged)

[MadhaviSeelam]

Verification PASSED using

Brave | 1.71.98 Chromium: 129.0.6668.70 (Official Build) beta (64-bit)
-- | --
Revision | 453ddf665beda526b19af7aa60047a0e757b6a7a
OS | Windows 11 Version 23H2 (Build 22631.4249)

Fresh feed every hour - PASSED

1. Installed 1.71.98
2. launched Brave
3. clicked Turn on News to enable news (at 12.16)
4. opened Tab 1 and articles show news updated as following
5. Good House Keeping 24 hours ago
   • Wikihow: 2 hours ago
   • Business Insider: 2 hours
   • Polygon: 4 hours
6. opened tab 2 and and it shows same
7. Waited for an hour (12:16 pm -->1:22pm)
8. Waited 3 hours

• Confirmed times for the articles on Tab 2 got updated
• Confirmed Tab 1 news feed is refreshed, and new article cards shown

Tab 1

1 hour

example	example	example

Fresh data every 3 (unchanged) - FAILED
Filed: #41276

Tab 1:
3 hours ((1.45 --> 5.53)

example	example

Tab 2:

example	example
3 hours (1.45 - 5.53 )