The svg-with-images case asserted that the stubbed rp/cmd! saw only the
URL upload RPC. clear-thumbnail sends :delete-file-object-thumbnails after
a 200 ms timer, so on slow CI runners that call was recorded too and the
assertion failed.
Count only the :create-file-media-object-from-url calls and expect one,
so unrelated RPCs no longer break the test.
AI-assisted-by: claude-opus-5-5