fix(sqlite): Empty the cache after the introduction of TimelineEvent::timestamp

[Hywan]

After the merge of #5648, we want all events to get a TimelineEvent::timestamp value (extracted from origin_server_ts).

To accomplish that, we are emptying the event cache. New synced events will be built correctly, with a valid TimelineEvent::timestamp, allowing a clear, stable situation.

This is required to also solve a performance problem. When using the new room_list_service::sorter::recency, the TimelineEvent::timestamp() method is called a lot (depending of the number of rooms). If the TimelineEvent::timestamp field is empty (None), extract_timestamp will be called to… extract the timestamp from the origin_server_ts value, which implies parsing the event every time. This value isn't kept in-memory at this step because TimelineEvent::timestamp() is a getter. The timestamp value is set during the sync. Hence the clearing of the cache: we restart from fresh, and we are sure all events will have a correct timestamp value.

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• Address [meta] Latest Event API, the missing one #4112 (comment)

[stefanceriu]

I'll trust you know this is all of it. Ship it! 🔥

[codspeed-hq]

CodSpeed Performance Report

Merging #5665 will not alter performance

_{Comparing Hywan:fix-sqlite-empty-event-cache-because-of-timelineevent-timestamp (6f34829) with main (c2bc465)}

Summary

✅ 49 untouched

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.37%. Comparing base (c2bc465) to head (6f34829).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
crates/matrix-sdk-sqlite/src/event_cache_store.rs	66.66%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5665      +/-   ##
==========================================
- Coverage   88.38%   88.37%   -0.01%     
==========================================
  Files         355      355              
  Lines       97472    97481       +9     
  Branches    97472    97481       +9     
==========================================
+ Hits        86148    86152       +4     
- Misses       7260     7263       +3     
- Partials     4064     4066       +2     

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