Fix unnecessarily writing send channel logs to the database

[rowanseymour]

We're currently writing channel log objects to the database that we shouldn't be.. channel logs are considered attached if they are referenced by a message, therefore don't need to be written to the database because they will be accessed via the message that has the UUID of the log so we can find it in S3.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.88%. Comparing base (2e65d7e) to head (5278572).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #760   +/-   ##
=======================================
  Coverage   75.87%   75.88%           
=======================================
  Files         111      111           
  Lines       10393    10394    +1     
=======================================
+ Hits         7886     7887    +1     
  Misses       1788     1788           
  Partials      719      719           

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