Complement runner configures the media worker as `synapse.app.generic_worker` instead of `synapse.app.media_repository`, which looks like it shouldn't work but apparently does

https://element-hq.github.io/synapse/latest/workers.html#synapseappmedia_repository

This seems to be the only place where the app name matters for the media repo: https://github.com/element-hq/synapse/blob/f95cfd898e1e8e649d513ac181ce6a0442b6a2e6/synapse/config/repository.py#L129

but crucially it does seem to matter! But the Complement tests are passing...?

https://github.com/element-hq/synapse/pull/16803#discussion_r1457341623

Start with Synapse's synapse/config/repository.py at line 129 and the media_repository worker documentation linked in the issue. Trace how Complement configures the media worker and compare that app name with the behavior exercised by the tests and the linked pull-request discussion. Done means the apparent mismatch is explained and the relevant configuration or test coverage reflects the correct media repository app.

Written by the indexing model from the issue text.