fix(timeline): maintain aggregations when an event is deduplicated

[bnjbvr]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 90.42553% with 9 lines in your changes missing coverage. Please review.

Project coverage is 85.43%. Comparing base (4c4dd03) to head (140ab9a).

Files with missing lines	Patch %	Lines
crates/matrix-sdk-ui/src/timeline/event_handler.rs	86.66%	6 Missing ⚠️
...rix-sdk-ui/src/timeline/controller/aggregations.rs	89.28%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4576      +/-   ##
==========================================
+ Coverage   85.42%   85.43%   +0.01%     
==========================================
  Files         286      287       +1     
  Lines       32213    32239      +26     
==========================================
+ Hits        27517    27544      +27     
+ Misses       4696     4695       -1     

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