sqlite: Drop media table from event cache store

[zecakeh]

Since the media store was split into a separate database in #5568.

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.34%. Comparing base (878e02b) to head (4706b45).
⚠️ 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	60.00%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5655   +/-   ##
=======================================
  Coverage   88.34%   88.34%           
=======================================
  Files         354      354           
  Lines       97097    97107   +10     
  Branches    97097    97107   +10     
=======================================
+ Hits        85778    85793   +15     
+ Misses       7266     7258    -8     
- Partials     4053     4056    +3     

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[codspeed-hq]

CodSpeed Performance Report

Merging #5655 will improve performances by 47.79%

_{Comparing zecakeh:sqlite-rm-event-cache-media (4706b45) with main (878e02b)}

Summary

⚡ 1 improvement
✅ 48 untouched

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	Restore session [memory store]	402.2 ms	272.1 ms	+47.79%

[andybalaam]

Great, thanks!